UNAUTHORISED DEBIT ORDER

My fiance had an unauthorised debit order for over R600 that went off his account on 30/9/2020. He went into the Port Shepstone branch to reverse it as he wasn't aware of what it was for and he didn't give authority either. The staff member informed him that they are sorry but they can't do anything as it's a non returnable debit order. Since when does a bank allow debit orders to go off accounts without authorisation and if it's queried, they just shrug and couldn't care less!! Will he have to give up his hard earned money (12 hour shifts) every money due to a unauthorised debit order that we can't stop at the bank due to their incompetency?? It BS!!!