MTN misleading upgrade and double bill.

I have had the absolute worst experience with MTN. For the last two months I have been badgered by MTN call centers to come and upgrade. I went into the store and still owed money on the contract, then was advised to come back on another date, when I arrived, surprise surprise still more hidden costs - so was advised to come come a month after my upgrade was due the day before my data normally kicked in, and was promised no hidden costs and a minimal pro-rata. When I received my bill it was literally double - so I was charged a whole month’s data for one day plus my new contract amount. I then emailed to enquire with no reply and then tried to phone 4 times and couldn’t get through! At every point I have been mislead and **** to.