Billing/account still not resolved

Refer to REQ:*** from my previous complaint last month. I had a reply saying that a management team will be looking into the matter. I never had any other feedback on this? Yesterday I received a statement from MTN. Last month's (January's) statement had an amount of R784.20 as a closing balance. The next statement (that I received yesterday) had an opening balance of R6129.33. Please tell me how this happens. There is no movements or explanations on the statements telling me what I am being billed for. This is getting way out of hand. What do I need to do or who do I need to talk to to get this sorted?