Unkonwn Uprgrade instead of a PROMOTION!

I was called on the on around the 8th of November about a data promotion which was called millennium or millennial and it would be R20 less than my current contract, which I understood as instead of R399 I would now be paying R379. I was however debited R456.50 for both November and December, I then called the call centre and was advised that it was loaded as an upgrade and that I am now paying more for the device. I did not agree to no upgrade as I am due for an upgrade in MAY 2024. I would like this to be resolved asap as my next debit order will be coming up, I will not be making use of Telkom's services in future if this matter does not get sorted! My phone's motherboard already gave me issues twice where I sat without a phone for a month each time now this!