MTN ***** and incompentence

I wanted to upgrade my contract in December 2020 and was told that I have already upgraded the contract in August 2020 with a 3rd party company called Rewards Co that MTN employed. This is after I opted out of any marketing with them on my contract. Secondly, I never agreed to any upgrades on the contract. I lodged an investigation with MTN and Rewards Co and I have been passed from pillar to post between these two companies with no results to date. Rewards Co simply closed the investigation saying that it is invalid after I was told over the phone that the upgrade was cancelled. I even asked for proof by means of the recording where the supposed upgrade was offered and cancelled which they refused to give/send me. I have been in contact with MTN and they are totally *********** regarding resolving this matter. I have a contract with them and not with Rewards Co and I find this to be absolutely unacceptable and **********.