Failure to close revolving loan

On the 8th of November 2017 I payed of my FNB revolving loan and went to the branch to make sure it is settled and closed off. I was told that they are having system issues and that the loan will be closed off. A week later the loan wasn't closed and I went to the branch again of which I was told the same story that they are having system issues. This week again the loan isn't closed off and I went to the branch again as they were charging me interest, I was told they are still having system issues and that it will be closed.Today I deposited an amount into my check account and the loan took the amount. I went to complain about this and they called some lady by the name of Antoinette who is an analyst at FNB and she reversed the transaction only because I told her I have a debit order that has to go off tonight. She was so rude and giving me attitude telling me that "she is not the system and cannot do anything". Please assist me in closing this loan account.