rpm, I don't buy this for one second. These issues having been going on for over a year. MTN have over-charged over R11,000 from people that I know alone, and their attitude has always been pay-up or we blacklist you.
I had a friend who was terminally ill, had just stopped working and was slapped with a R5000 cellphone bill for one month. He eventually had to borrow money from his parents to pay the bill. Not even going to MTN's office in Sandton seemed to help resolve the issue.
The plain truth is, that MTN don't give a damn.