Incorrect Billing on Data

Good day<br> <br> After 2 months of ridiculous high billing to Data, we did everything in our power to stop that. Even loaded extra Data Bundles before the limit were reach. On 19 August 2015 I did contact Loise from Cell Network and asked her on what the usage stand, it were on 103mb, She did load 2GB data bundle extra on top of that, while we waited for the sim card to migrate to 5GB and put a limit on that. End of the month they deducted 19812.10. How is it possible after we made sure everything is in place, when we contact MTN the credit controller no response. I want to know what is going on and want a full data usage report for May, June, July and August as this is ridiculous. MTN really have the worst service, NO SIGNAL 90% of the day, it's just terrible to be with this network that doesn't care.