Selling Cars with Defects

Be very carefull of these guys!!! They bought an Audi A3 at an MFC auction (I have the paperwork, they left it all in the glovebox), MFC did a full Dekra report on the car showing 3 pages of issues and error codes on the vehicle, one of the issues being the car does not go into gear at some times. They sell me the car, few months in we picked up this issue a few times. Now they claim they did not know anything about the problem, and its also not their problem but something I need to take up with Audi SA.

They are not taking any responsibility, although I jave all the paperwork that proofs that they did know about the issue and sold me a car with defects. How is this honest business? Or is honest business just not something you get these days?