PATHETIC SERVICE!!!!! NO ONE CAN HELP!

I opened new contract with Mtn on the 31 July 2015, got my first invoice 13 Aug 2015, I was billed in advanced and on statement it says first invoice will be charge pro rata, so i paid pro rata as well as one month in advance. I queried it, nobody came back to me, call centre cant help. From my 1 invoice i cant open itemised billing and can still not open it. I phoned on Friday once,21 sept twice and today 5 times. Every time they just send me my statement and invoice again and the link and when i click on link it says, sorry you are not subscribed for this service, although on my invoice i do pay for itemised billing. No one at the store or at the call centre can help me to get itemised billing. Does anybody have any idea who I can call to please help me. I came over from Cell C to Mtn and must say, it was probably the worst decision I made. Am looking at the option to go back to Cell C to help me buy me out of my contract from Mtn. Any Advice Please!!!!!