I'm pretty sure other tactics like saying "I only accept 11 month leases" because section 8 requires 12, are also asking for a discrimination lawsuit.My understanding on this (from lots of reading but no direct experience)  is that you can apply the same rental qualification criteria to a section 8 applicant as any other - credit score, prior landlord reference, criminal background check (except in seattle) and so on,  however when it comes to income you are only allowed to verify the tenants portion of the rent responsibility.   

You mentioned "they are offering their system for AUD$3.5K", BUT, it is certain that they will be pressuring you with up-selling tactics which will require you dip into your bank account / credit cards more and more.Australians in particular are seen as easy targets for these type of programs, because we (yes, I'm an Aussie) are shocked when told we can get into three bedroom brick homes for $Au75k that rent out for $750/m.

While it is not a difficult process (I have done my own evictions), unless you know exactly what you are doing you will make a mistake and it will cost you way more than an attorney would.I would try many of the tactics suggest here in the right situation but I agree with @Joe Splitrock I think you are dealing with a pro and you need your A-game or will be worse off than before.

I had to compile a list of answers/delay tactics, because they would catch me off guard and sometimes I'd say yes when I should not have, etc. 

However I will definitely being employing that tactic down the line.

It's by far the cheapest option.And odds are, that if/when they go get advice on how much they can sue you for, the lawyer/fair housing people will tell them they should be glad of what you've done for them, and they could owe you money if they sue you, so they should leave well enough alone.And, as I said, I'd tell the manager to forget about getting any more money from you, and if they disagree, they're welcome to sue you and you'll counter-sue them, as well.I've had excellent experiences using this tactic.  

More for your consideration:The following are links to information that the savvy investor would need to combine investment tactics and techniques to generate high yielding ROI.

I have done the general tactics as everyone else just seems like traffic is very slow.

@joshJosh, you might find a letter to the landlord is still worth a try, He sounds like a jerk but a stamp is all it's going to take to send him a response,, He's probably rented the place out again,, might be worth a heads up to the new current tenant about his tactics, Someone should stop him in his tracks.

I'm a retired programmer and know the IRS has programmed algorithm triggering of high risk returns based on the numbers and tactics found from a computer scanning basis.