Account not closed

I had opened an account in April 2014. I bought a few items , paid for it in full and closed the account. I have received confirmation that the account is indeed paid in full and closed. I tried to open an account this past weekend with Mr Price. They called me today to say that I have an account opened with NWJ RCS and have a monthly amount that has been accumulating which has not been paid for. I called NWJ call centre accounts and they confirmed that there is no such information picking up on their system. I called Mr Price back and asked for the credit results to be emailed to me which they have and it does show that I have a balance of R1733 owing on a revolving account. Please sort this out. I cannot afford bad credit rating.