ABSA Maponya mall branch worst service

A debit went off my mother's bank account which she has completly no knowledge of, so I told her not to worry but rather go to the bank and have that debit reversed and place a stop payment on her account. She went to the Maponya mall branch where she was advised that ABSA cannot reverse the debit she must contact the company. How does she contact a company she has no knowledge of? Furthermore, the debit went off again this month meaning the payment stop was also not placed on that debit. She has received appalling service from the ABSA Maponya mall branch.