Worst customer service on contract issues

I took out a Black Friday data Month-Month special for R199pm on 29 November 2022. On 20 January 2023 I receive a bill for this same contract for R436pm. When following it up, I am told that the contract expired and all discounts are removed hence the price. This after the agent specifically explained that the contract continues until I give 1 month notice to cancel. MTN is unwilling to address the issue and keeps to their response. Horrible customer service.