Customer ripoff

Revolving loan, finished paid and the account was suppose to be close. After 1 month the account ran interest of R139 and i received a call from FNB informing me i owe them after i reversed the amount and lodge a dispute. I told the lady i refused to pay a account that was close and she consulted with her supervisor and said she is going to close the account. The following month the amount went to R210 which i also reversed and lodge a dispute but i still been hassled to pay the account.