MTN DOESN'T GIVE A DAMN ABOUT ITS CUSTOMERS

Good day please assist me with an issue I have with Mtn which has been dragging on since September. On the 6th of September an Mtn consultant did a fradulent migration/upgrade on my contract and because it was after 5 when I saw smses that they did credit checks on the bureau and then another sms saying my upgrade was successful. Next day exactly 8 o'clock I called their customer care to enquire and the confirmed that indeed a migration/upgrade was done on my contract. I told the lady to cancel and she told me she has system issues and that an email will be sent to the person who made the changes to cancel.Then around 12 I called them again to do a follow up and the 2nd lady I spoke with told me that the cancelation was not done but she will assist me.We spoke about an hour as she did the cancelation. But to this day on their system the cancelation reflects but they failed to update my bill back to the normal instalment. It is now accumulating arrears and whenever I call them ,they tell me that the issue is being looked into.I still make payment on the normal instalment at their store but I have arrears which are affecting my credit profile as they are unable to assist since September. What route can I take now?I tried hello peter,their complaints department as well as their customer care.