Faulty billing and account system

I have a top-up contract with MTN. Yesterday I received an sms that my line has basically been disconnected due to costs incured, even though i had loaded data the previous week and still had 2 gb left. I had over 200 minutes and 400 SMSs Left... please tell me how I am still incurring costs??? MTN? HOW DARE YOU DISCONNECT MY LINE? I have been a customer for over 10 years and have never missed a single payment or debit. Is this how you treat your loyal customers? I called customer care, who just reconnected my line, but could not explain why I was cut off from after running out of data over a week back. I loaded data over a week ago. HOW CAN YOU DENY ME ACCESS TO THE DATA AND MINUTES THAY I HAVE PAID FOR BY CUTTING MY LINE??????!!!!!!????? If this happens again, I will be taking action as you are breaching your contract to supply a service that I am paying for. I will have my contract cancelled and will look at other service providers. So will my wife. Your rotten billing system and general substandard service will cost you. I don't just want loyalty points, I want decent service for being a loyal customer. Maybe you should put the same team who sell contracts in customer care. If you looked after your customers the same way you look after perspective clients, everyone would be much happier.