Standard Bank turns it back on *****ulent transaction

A *****ulent debit order by MTN to the amount of R4000 went off on my Standard Bank account. There is no such debit order listed on my banking app so I cannot cancel it as suggested by Standard bank when I contacted them. I was also told that they cannot assist me any further and I have to contact MTN to sort this out. I have been a loyal Standard Bank client for 40+ years now, I will be closing my account as it's obvious that my money is not safe with them due to poor security measures by Standard bank. Shame on you Standard bank for your total lack of concern for the safety of your clients' money and total apathy by not even trying to assist a client who reported a *****ulent transaction to you.