MTN Overcharging customers and not resolving the problem

I did an upgrade on my MTN Data contract on 20 November 2024. I have emails from the sales agent that confirmed that my contract was upgraded at a rate of R1069 per month. at the end of November, December and January they have debited R2700 every month. When I enquired about the bill in December, I was told it would be escalated. Now in January, I am told by an agent that the upgrade was not loaded thats why I am being charged the R2700. She said that she has escalated it with Billing and with her supervisor and there is nothing more that she can do. I dont know how to resolve this situation short of stopping my debit orders. it is unfortunate that I cannot give a Zero star rating as 1 star is the minimum. This is not the 1st time that I have experienced a billing problem with MTN