Standalone petrol card

Good day I have a standalone petrol card with FNB, I phoned last week and asked them to close it and send me a paid up letter. The lady told me she has send through a request for it to be done. Yesterday i got a statement and what do you know , now i owe them money again because of the admin fees and other fees that goes through every month. I have asked for it to be closed before this will happen and it was not done. Why do i struggle so to close accounts with FNB it is rediculous. I am not going away from FNB i just dont need that account anymore but no you struggle your ass off to get hold of them and when you do , they do nothing. I want that account closed immediately and i want that paid up letter before the end of today. I will not pay that m oney i owe now because i asled for that account to be closed before that fees where added. The account was fully paid.