FNB taking advantage of customers/clients

I am reporting this for the 2nd time now. I became aware that my account is overdrawn and I deposited money to correct it before I even received FNB’s notification of the overdraft. “FNB :-) Your a/c ..320303 is in excess. Kindly correct immediately or FNB may dishonour. FNB a div of FRB Ltd NCRCP20. 04Jan 07:00”. I still got penalized R82.50 that led to my account being overdrawn again. I feel that I can only be penalized if I don’t “correct immediately or FNB may dishonour.” FNB should reverse the R82.50 it debited my cheque account ********** 0303 yesterday.