Car track debiting amount for contract that was cancelled

Hi , I cancelled my contract due to the fact that I sold the car. I then made an arrangement to pay the remainder of my contract in monthly installments. About a month ago I got an sms that my account was being handed over to lawyer to my shock since they have been debiting my account. I then decided I should rather just give them the remainder of the money. I called their agent told them I want to pay the remaining installments and she assured me that the debit will be removed my from account. To my shock I was debited again for contract that I don’t have with them.