They are selling people's information

I had a loan with finchoice and I paid until I finished. Last year December I didnt pay so someone called me and a saying they are callin from Finchoice. I was suppose rto have finished the payment in December but now it was going on . A lady then called me again because they didnt get money last month but told me that the account was sold to them by finchoice last year. They were also provided with my account number. I told the lady that I will never pay because I have finished paying Finchoice and I will never pay the debt twice. This affects my credit profile