His statement is not the truth.
A dealer can
choose to make a repair at any time.
So they can't say "can't do anything" in the sense that they are barred from helping you.
They are free to help you if they want.
What does not exist, by virtue of being sold on Form 5, is a
duty to make repairs - that is, a "warranty" in the way most people understand it for used cars.
The use of Form 5 does not negate the operation of the Australian Consumer Law.
Have you seen
this page?
Lastly - have a look in the car's manual. See if you can find how to disable the immobilizer and/or the alarm (there is usually a key switch somewhere in the vehicle).
One other thing - if you go and get it fixed at a mechanic of your own choosing, you can't just turn up at the dealership with the bill and expect them to pay it.
