Unresolved over billings Poor service and attitude

We are over the past 5 years been a corporate customer with average billings of approximately R36000 per month for approximately 1000 data cards that are used nationally in our industry. Our billings have increased to approximately R 90000 per month. If this is correct, our account will be in credit and theoretically up to date. We believe that our charges have been erroneously duplicated. MTN's staff and systems is unable to provide us with an explanation for this. A network provider of this size and magnitude should have been able to assist us on various levels. Our business parameters are consistent and data charges are consistent against the number of SIM cards and usage. After numerous attempts to resolve this, no one to date can provide answers. Initially we were advised by certain MTN staff to pay what we would think is a correct amount. We have now been threatened with disconnection. The impact of disconnection on our business is significant. Michelle Bawa, their accounts manager willingness to be of service is appalling. She has told us to pay or take our business elsewhere.