you always need a roadworthy when you buy a car, even if you buy it from a car yard. so either she is confusing a roadworthy with something else, or she doesn't have the car in her name. you can not transfer a registered car into your name without a roadworthy.
if they sold it to you unregistered you'd need to take the car to QT yourself to get it registered (or sign a form to say another person is authorised to do so), has any of this happened?
and phatboi, just because i'm not blowing smoke up her arse doesn't mean i'm not helping. she clearly doesn't understand how car purchases should work, and i'm explaining that.