Poor customer service from MTN

I have been trying to cancel my contract with MTN for a few weeks now. When I call in and get transfered to the retentions department I am on hold for 40 mins or more only for my call to get cut or the person eventually answers but doesn't provide me with my settelement figure. I asked them to send me an email or an SMS detailing the settlement figure and they can't do that. The other day the team leader told me to exercise patience because they are very busy. I've requested call backs and no body calls back. I would not recommend MTN to anyone. The customer service is very pathetic. The reason I am cancelling my contract is because the airime I get every month is depleted in a matter of days and I know for a fact I haven't been making calls.