Horrible

I had a cellphone contract with MTN which was cancelled in October 2020. The contract included cellphone insurance which was also cancelled in October 2020. I have confirmation that it was cancelled on the 15th of October. To date I have received invoices that amont to R1 286.00 for s service that I cancelled. The account has now been handed over to Legal without any notification. I shouldn't be charged as the service has been cancelled. I have called MTN numerous times to try and resolve this dispute and to understand why I am being billed for services that have been cancelled.