MTN Horrible Service

The communication between MTN and Mondo is not in sync. I received a 10MB uncapped 400 fair usage line which I have been using, but I am being billed for a 20MB Uncapped 600 fair usage line. 1. I called MTN they directed me to Mondo point of sale. 2. Called Mondo directed me back to MTN 3. Called MTN directed me to a different department. 4. Transferred to that department transferred to another. 5. Told to cal 135 6. Called the technical they wanted a reference number.