My car was a write off last year

My car was a write off last year. When I tried canceling the contract, there was money to pay upfront which I didn't have so I carried on paying the monthly installments. Wrote to them again the money qouted was even higher than the one before. From April I have stopped paying so tgat they can contact me. They have and they noted that I do not have a car anymore but my name has been registed with credit berue