Terrible service, Retentions say anything true or not and ignore you once you decide not to cancel

I logged my 1st complaint on the 23rd October regarding my billing and MTN couldn't provide answers. I got an invoice for November of 868.14 and December 4241.56. I contacted MTN to cancel my contract and Lereko Mabeta C: +***8 *** and he advised there was a system switch and I will be billed normal and I shouldnt cancel my contract. He doesnt answer my emails or calls and its because of him I didnt cancel eralier than today. I'm not prepared to pay this after the advise i got from the retention consultant. I know MTN wont respond but I want the recording and will take this to the ombudsman.