MTN messes up my debit order and makes it my problem

I have been with MTN for 15 years on a phone contract. I added thier Fibre to the home service just over a year ago. This service was added to my account on my existing debit order payment. somehow they messed up my debit order details after years of payment and i get an MTN SMS saying i must pay R21,331.33 within 2 days or be cut off. No email or call from anyone at MTN to expalin anything. They cut off my phone service, I contacted the FTTH guy and he stated the the amount owing was wrong and they would reconnect me. The next day I was reconnected.....then a week later I reiceve the same SMS warning legal action and get disconnected again....

Still no expination of what happened with my account and how much could be owing. All my statements show nothing owing.

I spent 15 mins and got connnected with another service provider and the rates are much better....MTN can keep my line disconnected....they useless!!!