Incompetant service

Please check previous response to my complaint ref ***...I am so annoyed as you have repeated the same mistake and billed me xtra. Please advise If my business is no longer needed as I cannot continue to call every month to query ..its a fixed contract so I don't understand what is the need for there to be an error twice. So must I take it that as long as I stay with mtn I am going to have to query every month why my account is not being billed correctly. I still haven't received my funds from the previous month though mtn response was that It would be sorted. I need my money back into my bank account and this sorted out ASAP