Unauthorized irreversable transactions from Absa

RCCS J I noticed that I had A LOT less money in my account. I logged into my banking app and saw that an unauthorised debit order journal had gone off. The reference was JOURNAL RCCS BOS J. I called the ***** department and a lady answered. As soon as I mentioned the reference number, the call dropped. I called again and the lady who assisted me said that it was ABSA's collections department and that she could not assist me in this matter. I then asked her what would the collections be for. She then said "Mam, like I said, I can't assist you. You will have to contact them tomorrow." Is this even legal to just take money out of my account without my authorisation?? Why didn't I receive a notification as soon as the payment went off? This is the second time I have experienced this the first time it happened was around this time last year for an amount of R1800, My loan amount did not even go down nothing changed. I called in and no one was willing to help me, Is this what we should expect from a Bank that we have entrusted our lives to?