FNB MAKING DEBITS AFTER LOAN PAID OFF

I had a revolving loan with FNB. I paid of the balance. However, a debit order went through on the 01/02/2015. I called and the consultant Yusuf confirmed that the system shows that the loan has been paid of but he doesn't know why. I asked him to reverse it for me. He could not because his system doesn't allow him to make the reversal.<br> can someone tell me who is supposed to know how to reserve the funds if I have fully paid the loan. I WANT THAT TRANSACTION REVERSED!