Revolving loan

Bad service from FNB, I trusted this bank but now they are forcing payments on behalf on customers. I had R0 balance in my account, yet they debited money and honored those payments on my behalf, why?? There is no explanation of this, considering the pandemic and how people battle financially, they decided that they are not going to let the debit order unpay for their revolving loan,this is the 2nd month it's happening to me. I am moving banks, FNB just lost a customer Been reporting this matter and all the bankers are sending me from one department to another