Wrong charges on account by FNB

FNB did it again. I spend R19 (which was available) on my account and the following day they then charge their monthly fees which I was told will be charged beginning of the month resulting in the account being over limit. They then charge a R250 penalty fee. Think about it, R250 penalty fee for R19, which at the time was available. This is a highest order of *****ing clients and it needs to be stopped now. By the way this is not the first time and I need these fees reversed.