NON CANCELLATION OF CONTRACT WHEN REQUESTED TIMEOUSLY

I had an LTE contract with MTN that was coming to an end on 15 May 2024. I phoned MTN on 15 April to ensure that I gave a month's notice to cancel my contract. The lady that I spoke to assured me that my contract would be cancelled. When I received my new bill, I noted that I had been charged for an additional month. I tried to call MTN but I could not get to speak to an operator because the options given by their computerised system would not allow it. I emailed Customer Services x 2 and each time that told me that the contract was cancelled and put on Pre-Paid, even though I did NOT request a pre-paid line. I did not pay the installment due for the next month and they suspended my cell phone account. This forced me to make payment for a service that I was not using because I needed an active cell phone line. I am at wits end because I can't get anyone to hear my side of the story and to get the month's subscription that I had to pay, paid back to me.