MTN has bad service and ethics

After being a client with MTN, holding 4 contracts. MTN decided to cancel my main contract without notifying me. When i enquired I was told it can’t be reversed. Worse, when I called to change my banking details since my account was closed, I was repeatedly told that they are offline, till I stopped. Now I have paid them manually and no one can sent me a better showing that I’ve paid. I have been calling for more than a week and no one can assist neither can anyone put me through to Legal department. Their legal can not be called directly either.