Poor service and violation of POPI

Extremely frustrated with MTN, I do not have a debit order as I am on a month to month paying cash into the account the reason why this was done was due to there being ***** in my account, I have always on time paid this and do not have anything outstanding with MTN, today I saw they have me on the credit bureau for one month outstanding. I called MTN regarding this and they confirmed I do not owe them anything, I then proceeded to set up a debit order of which my monthly instalment is R100 when I checked the Debi check I found the monthly installment being charged at R359. Clearly MTN does not know what they are doing or miss using personal information how does such is mishap happen???? I want answers as how why and what reason was my account handed over?????? Totally unacceptable. Contact number ***