Mtn messed up my upgrade

An upgrade was done on my 083 number on 14Sept21.The Mtn Tygervalley consultant (Dominique) confirmed that i was eligible for an upgrade on that number, also saying I would be saving a lot on my monthly premium. According to her I was to start paying the Flexi30 premium from end October21. However, on the statement of the 27thSept21 I was fined with a huge amount in excess of R12000. After many going back and forth, given the Mtn runaround and passing the buck., the manager at Mtn Tygervalley confirmed that credit was processed, and apologised for all inconveniences. She said the monthly premium for the 083 number is R51.55, but soon after I was told via sms to pay in an additional R715.50. She, Shireen Palm Tygervalley managers said in person that it was a once off payment. The following month I had to pay in a large amount again, and so it never seems to end. Agter many, many emails, hours of phone calls to customer service and customer complaints, driving in person to Mtn Tygervalley multiple times, and speaking to people at head office, it is still not resolved.

In a desperate attempt to have Mtn sort out their mistake, I have stopped payment and started to complain publicly and if necessary take it further.

The mistake is either consultant, or Mtn (IT) system, or both related.

MTN must sort out their mistake!