Bought a second hand car

From the start there was delay with car collection, not informing me about the delays only when I contact them. They lied about servicing the car, did not recieve my contract and other documents. Delay of number plates. Ten days after having the car problems was found and it was took back. I asked for refund or replacement was told they have the right to repair only if they cant repair can i get refund dont explain to me why i cant get a replacement. After the car has been there a few days, i got it back yesterday but the sound was not really connected to the radio/cd player and every time there is bump in the road or thump on dashboard sound is cut off and mech error appears. The car dint want to start this morning. Starter not working and i did inform however the person never came back to me after it was said they will contact workshop. I sent messages and phoned no response. Only a while afterwards that they will contact me on Monday when workshop opens. Im deeply upset because i paid a lot of money for a piece of junk. Being treated like this is not right and not being taken seriously. Bad services and will never buy anything there again and won't recommend it to anyone either.