getting charged for data used

on April 17 i was billed for data usage that i did not use and although there is a set limit of R1300 on the account it was exceeded by R4712 and then only was the services suspended why have a set limit then i want this resolved as well as reimbursed for the monies taken as i was not using the phone for that time said. I have been phoning customer services on numerous occasions to no avail then i was told to mail their legal dept which i did on the 18th of August where they sent a response that they would be attending the matter within 24-48 hrs it`s now 33 days later still no response. They just seem to read peoples queries but do`t respond to them this has been the worst service i have ever had and would definitely not recommend anyone to take or open any accounts with MTN