Highway *******

I have just been chatting to Nomfundo Sikhosana, one of the bankers at FNB, I as inquiring about a charge that took place in my account yesterday 08 Jan 2020. She informs me that the bank honoured a transaction where there was insufficient funds in my account, my question is, How can the bank do that, If i have no money in my account they should have declined the said transaction because I never requested for this service, therefore I should NOT be liable for bank charges for something that was entirely not my fault. Where in the world have you ever heard of such nonsense, I hope, through, her escalation, these charges will be reversed and something like this never happens in the future, she gave me ref number R*** and said I will receive feedback within 3 days.