They sold me a s**** and not willing to change it

I bought a car audi A4 last year . Auto pedigree Newcastle sold me a car that had a mechanical problem and the knew that it has a problem. I didnt drive the car 3 days the car had a problem . I sent back they checked . Within a month the car was overheating they took it in for repairs and three weeks later they gave me the car I drove it two weeks car started overheating again . I have been paying for the car that sits in the workshop . I have lodged complains and wants to swap out car they have been dragging the matter . I have spoke to Vinay Singh who is now not answering my calls no replying on my emails . I have complained to their complains department no . I am disapointed with Auto pedigree sadly I had trade in my car and now i am sitting without a car