My original post was to get clarification on whether a rent increase of 20% during contract was legal. I don't mind the banter providing there is some useful feedback hidden in there.

I think that's the main issue.

Let's face it, renting isn't necessarily the most secure method of living - the landlord can decline to extend a contract at the end of the fixed term so the renter would need to look elsewhere.. but they shouldn't be able to put the rent up during the period of the fixed term.

We rent in South Australia and I have 2 addendums added to every lease
1/ The rent cannot be raised for the fixed term of the lease.
2/ That if the landlord decides to sell we can break the lease without any break lease fees or costs.

Good idea but 2/ would be better if you added "without having to give the full month's notice to leave".

I have the impression that, if you try that in areas of high demand, that the landlord would add two words as well
1/ ****
2/ Off

They appear to be perfectly reasonable requests. I've never lived in a rental property so haven't had that experience. It would seem unfair to sign a lease agreeing to stay for 12 months, & be legally bound to it, only to find the landlord doubles his price after a month. Surely there's some protection in place to prevent this?
I have done plenty of evictions & property repairs on rental accommodation though & both my kids rent property. Some landlords are bloody shocking & bodge places up to make a quick buck, others build nice new homes & rent them as part of an investment portfolio.
My son rented a property in Waikiki when he first arrived in W.A his landlord agreed a rent price fixed for the term of the lease. Unfortunately he [landlord] couldn't keep up the repayments & the bank foreclosed on him. Our son was evicted without notice by overzealous bailiffs who tried to take his own personal property. A quick call to some of his navy mates solved that problem.

I wish I could find a tenant with integrity but thin on the ground here (and there)...

I believe there is, but from all I've heard about renting, most landlords are not going to agree to anything, that goes above and beyond their legal obligations.

A landlord would be mad to try and do something that is not in the lease as the tenant has more rights than the landlord.

Not sure how it works but if you sign a 12 month contract surely an unreasonable rent increase is breaking that contract
Most of my work in the U.K was for Landlords so I can see both sides of the coin.
Someone living on a pension has a fixed income if landlords up the rent each month they have no choice but to move on. I'm curious as to if that constitutes breaking the lease agreement.
As Zulu says if you don't like the increase move on, that shouldn't mean paying a penalty to break a lease when the rent has gone up to a point you simply cannot afford though.
Personally I'd rather have a good tenant that paid a bit less rent on the dot & looked after the place than always upping the rent, chasing tenants & having to keep repairing & painting. My folks initially refused any unemployed tenants, they later found that those were often the most reliable house-proud tenants that kept their investment in tip top condition. Dad was so impressed with the house when he did an inspection he dropped the rent back to the original price so the unemployed single parent stayed put. It had gone up 3-6% per annum on the advice of the property manager.

This from WA dept of Commerce, consumer protection for tenants....

Rent increases

The laws relating to rent increases vary, depending on what type of tenancy you:

are in a periodic tenancy, rent may be increased only at six-monthly intervals but you must be given at least 60 days’ notice in writing, with details of the amount of the rise and the day it takes effect. You only have to pay the increase if proper notice has been given. Rent cannot be increased in the first six months of a periodic tenancy, or less than six months after the previous rise.

rent in a fixed term tenancy cannot be increased during the term of the tenancy unless the agreement says so and it is at least six months since the last increase.

Excessive rent – paying too much?

The amount of rent charged at the start of a new tenancy is generally controlled by market forces, but if you believe the rent is too high you can apply to the Small Disputes Division for a reduction, or to argue against a proposed increase.

The grounds for taking it to court are that:

since the tenancy began, there has been a significant reduction in the contents or facilities provided with the premises; or
the landlord was putting up the rent by big amounts to force you out.

That seems a very fair way of doing things, much more civilised than the Queensland way of doing things

Pretty much the same in Victoria as WA by the looks of it.

I'd like to say that I have new information to report but alas the girl hasn't got back to me with a copy of her contract. Thanks for all your feedback anyway and I'll come back and post an update just as soon as I have one.

The way it should be - if (generic) you doesn't like that, don't be a landlord.