Disappointing And stressful experience

Since this month( September 2020) I have called MTN on multiple occasions as I have been receiving emails that my account is in arrears which it isn’t. I pay my account every month and have proof that it is paid. They have disconnected my lines and I have to call them to check what’s going on. When they check the system it shows it is up to date with payment. And say they will log it with the account department however no one is telling me that the error from MTN’s side is sorted out. I sent proof of payment but my query is left unresolved. It is unprofessional as I know I make payments then yesterday I get an email stating I’m owing 14000 which doesn’t make sense if my account is paid every month. Because of the incompetence of the account department my name is going to go bad. And all they do is apologize and say they going to sort it out but don’t. I don’t know what else to do. As no one is really helping me to state my issue is resolved. I am very disappointed with MTN. I used to say I don’t have any problems with them but now I don’t think I would be recommending them to anyone. I have 5 contracts with you guys and I think as it is coming to an end I will be cancelling them. This has been an extremely stressful and disappointing experience for me I have been loyal to MTN for a very long time.