Poor service from MTN

I currently have a contract with MTN that is about to come to an end. About 2 weeks ago a rep from MTN called me asking permission to change my data plan to airtime, as I don't cosume all my data within the month. I asked him if it was possible to still get data on this plan and he said I can convert the airtime I have to data on their MOMO app. This turned out to be untrue, because contract airtime cannot be converted. I had also converted my debit order date, and it was not done correctly. They still debited my account. I have been in communication with them to fix it, but they are not helpful or forthcoming. This is the very last time I am dealing with MTN and their poor customer service. I have dealt with them for far too long. they obviously don't need my business.