There are over 1.5 million renters in Australia, 15 per cent of them cause trouble. But what would you do, faced with a bad tenant that refuses to get out? Tim Noonan spent six weeks with real estate agent Renegade, Len Pretti, fighting rental wars against Australia's worst tenants.

Len Pretti: Gimme my lease. I want the lease. Give me my lease.

Len Pretti: People like this have got to be stopped.

Len Pretti: Hang on, Hang on.

Len Pretti: Give me my lease.

Real estate expert and author Neil Jenman: It's a dirty business.

Len Prettil: Gimme the f *** lease.

Len Pretti : Pay up, or shut up. I'm going to lock you right out now.

Real estate expert and author Neil Jenman: I think that a lot of people when Len Pretti's getting the job done on their behalf, they kind of turn away a little bit just so he'll get the job done.

Len Pretti: You're threatening me with a steel baseball bat, what a fool you are

Len Pretto : I step in where other agents fail.

Real estate expert and author Neil Jenman: When tenants terrorise landlords, Len Pretti's the guy you call.

He's got a bad name to bad tennants.

Len: I've kept that reputation, the agent from hell.

Kicking them out.

Len: Don't come back!

Chasing them down.

Len: When are you going to pay the money that you owe, the $9000?

And making them pay.

Len: I'll hunt them down and I'll kick their butts.

He's the repo man of last resort. Real Estate Agent, Len Pretti, has made it his life mission to even the score between landlords and tenants.

Len: There's institutions protecting tenants. But what institution protects landlords? Nobody.

Len (to tenant): You're going to be followed, you're going to be caught.

Every eviction, every collection can get ugly.

A tenant tries to run Len over.

Len: Am I supposed to be scared?

Len: You've got a baseball bat in your hand and you're threatening me?

He's been knocked out.

Tenant: Go home!

Pushed out and thrown out, all in the line of duty.

Mohammed: He's got a shit attitude...

Len Pretti: It's my f****in' lease, give me the f****in' lease.

Mohammed: He needs to fix his attitude at this age.

But at 57, Len is still determined to right rental wrongs, despite the danger.

Neil Jenman: Len Pretti literally puts his life on the line for his job.

Mohammed: Who are you, I don't even know you. I've signed a lease with Sam, who are you?

Len: I'm the new managing agent, read the letter.

Len was the last stop for landlord, Sam Cavallaro.

Sam: Well, i've tried other agents, but all we had was meetings but nothing seemed to be going on (he is interrupted by mohammed)

Mohammed: Outside, get out.

Mohammed: What's the problem?

Len: you're not paying rent!

Car dealer, Mohammed, hasn't paid his rent for three months. Len has come to collect.

Mohammed: Go call the police.

Len: You go call them.

No rent, no excuses.

Mohammed: You've got no right to come into my property.

Len: They spin you lies left, right and centre just to protect themselves.

Mohammed: He promised, in February, that you pay this month's rent and we'll fix the roof, we'll fix the downpipes, we'll fix the hot water and nothing was done.

Len: He had minor, very minor leaks to the roof, very minor. He had no hot water; it was a fuse, that's all it was. Nothing major at all, he could have changed the fuse himself.

Mohammed: Shut your gob and listen to what i've got to say!

Len: Shut your gob?

Len: He treated the previous managing agent like an asshole, he thought he could treat me the same. Well you know what, he couldn't.

Len: I'm going to lock you out now. I'm going to lock you right out now. How are you going to do it?

Len: I'm going to change the locks now to your premises and you're not going to go back inside there.

Locksmith changes locks.

Len: Is there a deadlock on there?

Mohammed: Don't touch my stuff...

Len Pretti: He actually snatched from me the lease and wouldn't give me the lease back. so that's when I lost it, I took my glasses off and said, right so if you want to punch my lights out you can do it and we had a bit of an altercation in the office where I won. I just don't back down. i'm supposed to be intimidated by them, i'm not intimidated by them at a, I do my job.

Neil Jenman: If he wasn't a real estate agent chasing tenants, he'd be with the anti-terrorist squad chasing terrorists, he's that sort of person.

Real estate expert and author, Neil Jenman.

Neil Jenman: Technically, you could probably say he doesn't cross every I and dot every T, so you might be able to point the finger and say, ah, Len Pretti broke the law. But from what i've heard, Len Pretti upholds the laws of what is fair and what is right.

Samantha: You are nothing more than a con artist and a liar. You are destroying everybody's lives...

Len: Some tenants, you know, do you realise this? They think they own the property, even though they're renting it! Can you believe it?

Woman: Move off my veranda.

Len: It's not your front veranda, it's the landlord's front veranda, you're only renting it.

Another tenant has taken this house hostage.

Landlord Samantha Cox: When are you intending to pay?

Woman: You need to leave (she slams the front door).

She owes the landlord Samantha Cox nearly $10,000 in rent...

Woman: You need to leave (she slams the front door).

And is refusing to move out.

Neil Jenman: Tenants who know the system, they can move into houses and just sit there, pay no rent and they're like squatters, they're very, very hard to get out.

Samantha: She actually stated, by the time she was finished with us, that she would own our house for nothing.

Len: Let me tell you something, you are going to pay every dollar that you owe this landlord.

Len: She owes $9100 in rent, so she's a scumbag.

But the ordeal has cost Samantha and her husband, Steve, much more.

Samantha: It's cost us our family, our home and probably our marriage.

Len: So this tenant's done three bites of the cherry. Rent, damage, marriage.

Len (to samantha): We...will...get...her.

Len: My job's to stick it right up her. We want to pounce her.

Len: I nabbed her when she was going to work.

Len: I gave her an ultimatum, pay the rent, otherwise i'll blacklist you. So she wanted to pay the rent.

Len: I hate tenant lovers with a vengeance.

Len makes no apologies for his heavy handed tactics, but he has his critics. They say he comes on too strong.

Lawyer Leigh Johnson: It's pretty nasty the stuff that you do when you're going in.

Lawyer, Leigh Johnson...

Leigh: I think when you're really abusive to people there's an ongoing effect.

Len: But what would you do if that what was of your tenants? Leave them in the premises?

Len: I would love to be able to lock a tenant out if they deserve it. Like you can in the retails tenancy services and

Leigh: But you do!

Len: No, I lock them out with a court order.

Chris: That's pointless conflict.

And Chris Martin from the NSW Tenants Union.

Chris: A property manager should come up with a sensitive, sensible way of dealing with problems that don't lead to big conflicts that don't lead to shouting matches, productive way of running a business.

Leigh: You are incredibly aggressive and incredibly intimidating and threatening.

Len: Do you blame me when I go into places that are totally destroyed?

Len: To go inside some houses you dry reach.

Len: Some of my property managers will not even walk inside some of the houses we take over you've got no idea.

For nearly forty years, Len has witnessed first-hand, the worst of the worst.

Len: We're walking into a place that's been demolished. (len lifts roller door).

Zena and her son, Boris, had their house destroyed by a tenant who didn't pay the rent and shot through.

''Wrecked kitchen, this room here looks like a bomb's hit it''

says Len.

Boris: It looks like a cyclone has gone through here.

Len: It was a wreck.

Len: Look at this, he's even had a fire in here in the lounge room look at that, he's cut the carpet, he's put the holes in the walls here, floors ripped up, tiles ripped up, doors smashed, windows smashed, stove pulled out.

Len: The guy's just a pig, total scumbag, pig.

Len: Got to look for money, mate! You'd be surprised what you find when it comes to tenants.

Len: He couldn't pay his rent, but he could leave all that money behind.

Len: Thousands upon thousands of dollars worth of damage.

Len: He won't pay the money but you know what we'll do? We'll bankrupt him.

Boris: I hope he gets what's coming to him.

Len: we're going to get this guy's address and stick it right up him.

Len: Makes you cry.

Len: When you go through a house and the landlord's crying and they're so emotional it affects you very badly.

Len: You can't let him get away, you can't let him get away.

Neil Jenman: If a tenant moves in and on day 1 stops paying the rent, it takes you six weeks to get them out at least. That doesn't count the damage they can do to the house on the way out.

Len: At the end of the day, this guy is paying for these people's livelihood. They've worked very hard, they need the money to pay the mortgage off.

Here's the scenario, you've scrimped and you've saved and you've gone without...for that rental property, that investment for your retirement. Then, the house is taken over by a tenant, who turns into a terrorist - a home invader that you can't get out. Well, what are your rights? According to Len, you have none.

Len: When you get tenants like this, this is where the rental industry's wrong, this is where the laws are wrong (butt to) you can get a video and get charged $5 for late fees, you can pay your water rates, council rates, your land tax - you can pay 15.38% for paying your land tax late. But you cannot be charged anything for paying your rent late, so where's the incentive for paying your rent on time? Nothing.

Len says we desperately need the Tenancy laws to change.

Len: A lot of these clients are only one house property investors and they rely on the money, they rely on these properties to be looked after, they rely on the income to pay off the interest, let alone the principal. Now you get a bad tenant in there, my god almighty, the poor landlord loses.

Until then, he'll defend the landlord, no matter what the cost.

I don't give a f**** who you are, because you know why? I've had double barrel shot guns rammed down my throat and you know what I did? I didn't back down and it was loaded. You want to kill me? Go for it! Put me out of my misery!

Leigh: I think that when you're really abusive to people and I think there's an ongoing effect.

Leigh warns that pushed too far, bad tenants can do bad things.

Leigh: Sometimes when people crack they wake up on a Saturday morning, run down to the shopping centre and shoot everyone inside.

Len: The office is built like a bank because at the end of the day, some tenants do come in and they are very aggressive.

Ten years ago, an argument in Len's office ended in bloodshed.

Len lives with that nightmare every single day.

Len: I wouldn't wish this on my worst enemy.

Neil Jenman: He has lost one of his people, they've literally put their lives on the line.

Len: We've had our windows shotgun blasted, they are now 11mm bullet-proof laminated, because obviously the way I am with tenants, i'm pretty hard.

And that's where the debate now lies, how far is too far to collect the rent?

Neil Jenman: I'll bet you that Len Pretti is a fair man if you sit down and talk to him.

Mohammed: In your point of view do you think you're a good real estate agent?

Len: I'm a good negotiator.

Mohammed: You're rubbish, mate.

Neil Jenman: But when you tell him lies, when you cheat, when you hide, then you're likely to find Len Pretti's going to be, you know, coming out of your cupboard in the middle of the night.

Mohammed decided he'd rather pay the rent than be locked out by Len.

Len: I said, look you've got two choices, pay your rent or otherwise give me the keys to your factory so what did he do, he paid his rent.

Sam shakes Len's hand.

Mohammed: I think he's a dodgy real estate agent.

But Samantha and Steve would disagree.

Steve: I could just cry. It's just a joy to have her back.

They now have their house back.

Steve (cries): It's just great to be back, to see it all in one piece.

Samantha (hugs len): Thankyou for getting our house back!

Len: From the tenant's point of view, i'm a very bad person, well you know what, i've got plenty of tenants, but i need more landlords.

Neil Jenman: The rental department is the toughest job in real estate and Len Pretti is the toughest man, doing the toughest job.

Len: Me a cowboy, no i'm a professional property manager that's what my job is if i'm acting illegally, go get my licence suspended, I don't mind! I need a holiday anyway.

Len: You know that if those cheques of yours bounce. I'll be back.