Account Dispute

I sent Mtn an email with regards to account billing dispute on 23/02/2015. Received email response 26/02/2015 stating query has been escalated to Credit Management. Since then there has been to response to my query. I called on 04/03/2015 and was put on hold for 18 mins. I called again and spoke to Bheki who informed me that there was no query with regards to my account although i gave him the reference number ..... [#***] which was given to me. I asked to be transferred to Credit Management and was promptly cut off. ON Friday 6/03/2015 i received sms stating i will be disconnected if account is not paid. I called the call centre on 5 occasions explaining the entire problem every time.....and was promptly cut off when transferred to Credit Management. How does one rectify a query when you cannot get a response ???