Bounced Debit orders charges R100

I have an FNB account, this month alone I had one debit order bounce and when I check my statement it written 'Magtape overdraft' - R100. I had a chat with one of the ladies over the FNB app who then told me it was for the debit order that bounced. I never received an email or a sms to make me aware that my bank charges will increase and this 'Magtape ' I have never seen it any of my statement. The lady I was speaking to via the app told me to login to the FNB website and I will be able to see the rate changes but I didn't see anything about 'Magtape' or changes on bounced debit orders being a charge of R100. It this point I really want to leave FNB and find a better service provider but been with FNB for over 10years now.