Debit order reversal

I am angry, frustrated and disappointed with the bank. There are 2 debit orders that are going through my account the other one in December the bank managed to reverse it for the amount of R750. The other one they could not reverse reason being the debit was mandated. I was given numbers to call the company and I can not go through.

This month both they can not reverse again reason they are mandated. My question is how did the bank managed to reverse it in December. I am told that I must open a case and they can only suspend the debit orders so that next month they dont go through but it's not guaranteed. My money its not safe in this bank because I did not gave anyone a mandate. The other company debited on the 20th of this month just because there was funds in my account.

If I wont be assisted with this today there are banks that are waiting for me to join I can't waste my time to call and be told that there's a mandate while I am not aware off. Someone must assist me with this matter