Taking money unauthorized

I am frustrated with ABSA. Last month they deducted R 6000 from my current account for my credit card thats in arrears. I then made an arrangement to pay R 250 per month which I did adhere to. Now AGAIN they decided to deduct R 1200 after they PROMISED they would not deduct again if I made an arrangement. AGAIN they are going against their word. This is unacceptable and not what was agreed. It is theft to just keep on taking my money when I adhered to our agreement. UNACCEPTABLE.