MTN INCORRECT BILLING

I have been an MTN customer for over ten years and had renewed my Black Friday contract on 20/11/2018 . Previously MTN have called to renew this contract and that’s how it was done in 2020. Today on the 19/11/2020, I tried to renew my contract on their app and noticed my bill was R6200, whereas my bill is usually R600 per month. After calling MTN, I was informed that I was charged out of bundle rates due to my contract ending and I was apparently informed. This is absolutely disgusting and **** poor excuse for service. I was never informed or ever issued an acknowledgment of out of bundle rates. Why was I not called or even emailed and given the option of whether to continue at out of bundle rates? Why is the response of MTN call centre agents that “MTN told us clients were informed” yet have no proof on their system that an email, sms or call was done . This is absolutely ridiculous. I will not be paying this until I am shown the confirmation for where I accepted out of bundle rates . I will be laying a complaint with ICASA