Excess Account fees

Good day ,

I'm so dissapointed in FNB. My Premier cheque account has been in excess because i pay for purchases online. Every other time when it has been in excess no fees for unpaid items has been deducted. So my question to them is ..Why hasnt this happened prior to this month ?? Its a R110 for every transaction i mean they can use the R110 only why should they deduct a R110 for every transaction. Would it be unfair to ask my money back if i wasnt aware of this?? I honestly havent knew about this at all.

Can someone kindly advise me on this matter.

Thank you