Poor service and communication

I have been trying to reach MTN for 5 months now regarding the listing on my credit profile.My account was paid in full however i still have a hanging listing that i am handed over. 2. I have also received a notification yesterday that my account is overdue like how come because i am not using it and i have asked for you guys to close this account long time ago.This is really disgusting because you dont answer calls, i stay long on the queue and then you dont even respond to emails.What does one have to do in this situation because you have ruined my credit profile then you come back to say i owe again even after i have asked several times for account closure.How come i now owe you for a service that i am not using and asked it to be cancelled.Kindly assist as i have ran out of energy to make means of reachung out via phone calls and emails.