Bad service from FNB

I'm really not happy with the service I received from FNB I have requested that a debit order which it was not authorised to be stopped and to my surprise the company managed to debit I spoke to the other agent from FNB Premium Help desk to explain to me how did that happened she told me that she will get back to me even now I'm still waiting still haven't received any feedback. I don't feel safe anymore to bank with FNB because I feel like my money could be debited by unauthorized company.