Upgrade / Prepaid

Mtn is the worst service provider I ever had. I have had my number from the time i was in school, as soon as i started getting contracts with them then they service levels drop to the ground. MTN is unable to upgrade my data contract due to the fact that none of the staff have any idea what they doing. I have tried to be upgraded 3 times an i paid the new tariff and never got the upgrade and never got refunded either. I also was billed incorrectly and paid that amount as well. I called at least 3 times a month and no one can help or transfer me to a Manager. I tried to go onto prepaid then was given a merging contract (Which none of MTN customer service agent or accounts department knows what that is, because i keep getting charged.) All i want to not upgrated and my number to be prepaid how hard is that ??? I keep getting charged and blocked by MTN and none can give me the answers. I am still blocked and still no onw can help. This is the most frustrating company to have service from.