MTN accounts

I cancelled my MTN number in December 2019. When I did did the cancellation was told that it would be done within 30 minutes and would go onto pay as you go. As I wanted to move onto another service provider, I was happy with this. Found out in March 2020 that MTN has handed me over for non payment. I received no email or sms notification of outstanding balances. After a number of phone calls, found out that that MTN has not picked up a payment I made at the end of November. MTN states that they can only pick up payment at the end of October. Even after sending MTN legal proof as well as CSS solutions “ who do there bad collections “ I have had no joy. There is no one who you can contact and service levels are non existent.