I have purchased a used Audi from a local dealer.

They offered a three-month full warranty with the vehicle.

Unfortunately the car has been back to the garage on several occasions and has cost the garage a considerable amount already. The main fault with the car has not been identified and they are struggling to diagnose the problem.

Where do I stand once the dealers 3 month warranty expires?

If they have not fixed the problem that has been present since I purchased the car, are they obliged to fix the fault as it was present during the warranty period? Or can they leave me with the problem to fix myself?