Overcharging after contract expired and misleading information from customer support

Just before my contract was due to expire in December 2020, I contacted MTN to enquire if I would still be charged the same amount now that the contract was expiring.

The person I spoke to on the phone notified me that “I would remain paying the same amount even though the contract was expiring- R299 for a Sim Only Deal - My MTN choice 30Gigs.”

I have now received a bill for over R1000 and when querying this, I was notified the price changed to the regular pricing and that's why it was so high now in January.

I tried, unsuccessfully, in multiple platforms, to lay a formal complaint regarding this matter as this is not the first time it happens to MTN customers.

Please see link and article below. The article speaks about this issue on Nov/2020.

https://mybroadband.co.za/news/cellular/376649-mtn-customers-on-black-friday-deals-slapped-with-huge-bills.html

So far I got no answers from MTN to let me know how this will be corrected and how I will be compensated for the amount I will be overcharged in my next bill.