4 months no resloution

May 2015 billing was R5 719.50. Reported incorrect billing immediately and went to Hillcrest branch on Sat 31 May 2015. Talissa gave us a billing query number of *** was given to us. They said 5 days we would have an answer. Monday 1st June I phoned in and was given another number *** by Morne in CT. Never heard from them. This phone has an automatic block and one cannot go over R730. If you reach a limit it soft blocks and then you have to phone and buy more data. Mtn tells me that this phone number is an open line. That's all I get from them !!! It is so frustrating. I had to go to bank in order to stop anymore stop orders coming off and now the phone is blocked. When I phone Mtn help line I have been told that this telephone number does not exist and now also been told that the account is under someone else's name and a business contract. All this time they keep sending me monthly invoices with varying amounts and the phone is still blocked so this could not be possible. I am beyond exasperated. This is not a new contract and is up for renewal end next month. So if the contract was open then why the big data usage now and plus can't happen as it soft blocks. HELP PLZ !