Bad after sale service

I 2022 my contract ended with MTN . I was never informed that I had to cancel the number myself. MTN kept on billing me for the ended contract. In September 2022 and numerous times after that I requested the number to be cancelled. It was never done and I had to pay for months for data that I could not use. The number eventually got cancelled and I requested a refund for all those months that I had to pay to keep my name clean. Every email had been ignored. An automated reply that they would look at it is not enough. I kept on sending emails, with no communication from MTN. I am fed up.