Mtn billed the incorrect account

I recently changed my bank details for my debit order and called MTN on 18/19 September and spoke to Ndileka at 13.50 and asked if I could change my banking details telephonically. I was informed that it was fine and she verified me and took my new bank details down. I was given a reference number and was told that everything was fine. To my surprise on 1 October, the debit order was collected from the old banking details. Today I called and spoke to Proffessor who informed me that they do not change banking details and that it would need to be done in store. I became very furious as I now feel like I am being taken for a fool. He then said they escalate the change of banking details to a different department and that I would need to call in about 2 or 3 days to confirm that they have been indeed been changed. I was given another reference number for this to happen. These banking details need to be changed ASAP and I am tired of the run around the reasons your different consultants have. The main reason I have to do everything telephonically is because I cant even be found on the system when I go to the MTN store. Contact me ASAP and get this resolved please