My first suggestion is too old to be of help now, but before purchasing any second hand car, take it to the Automobile Club of the state you are in. For me in Qld it is the RACQ. After purchasing my brand new car and just prior to the warranty expiry, I took it for a pre-warranty expiry check. Cost me $200 but it found a few faults that the dealer had to fix by law. Having a check by the state club is the best way to decide if you really want to purchase that car. Some faults are just too troublesome for the dealer to fix so they patch it to get through the roadworthy. Alas though, any "verbal" agreement is not worth the "non-paper" they were never written on so sorry, you do not have a right unless it is a roadworthy issue.