Debit Card Fees

FNB please xplain why I am constantly getting R8.50 deducted off my account? It says it has something to do with my card being swiped when there are no funds in it. This is nonsense. On the 22nd January you deducted R8.50 seven times in a row!!! And then again on the 25th January. I know for a FACT I had funds. Why are you *****ing our money so blatantly!!!!