Poor customer service from MTN

I have been an MTN client for over 20 years. In April this year I contacted them requesting to convert my contract to prepaid. The contract was linked to two other numbers used by my kids. I left my job to pursue other interests. When I called I was advised that I should wait for the contract to end in May to avoid penalty fees. So on the 3rd of May I went and paid off the balance owed, I called the number provided to cancel. I also sent email to cancel, to my surprise, on the 12 June I received notification that data bundle, minutes are loaded. Then I sent them an email asking why am I credited after canceling. I even got an email asking if I want to convert all 3 numbers, and I responded yes.

I have been asking them for cancellation till June and kept sending emails for them to correct this on their system as I was getting statements that I owe.

Eventually, I stopped emailing, until now recently ( in November) when they blocked my number. I went to their head office and still today, this is not resolved. I am in Real Estate business, my number is important for conducting business. As a result I have not been getting my enquiries.