FNB loan payment

Ref: *** Acc: *** Amount to pay: R325.00 FNB legal department: *** FNB still has not helped me regarding the confirmation letter of payment what they did now is telling me that I owe them R80 when I asked where does that R80 comes from they can't give me a valid response where it came from since my loan is fully paid. They said they will get back to me until now they have haven't I need answers where is that R80 coming from cause I have completed my payment. Hellopeter please help I need clarification on this issue.