Incorrect billing

Yesterday I called regarding a 2nd debit going of my account for Vodacom, the consultant advised he was unable to assist due to system issues and will call me back, and that the entire Vodacom has issues with the billing or account systems, being as that may be, this has nothing to do with me as a client and am still waiting for feedback after 3 follow-up emails and a promised call I haven't received any responses, this may not be important to Vodacom but it is to me, since day one I have been having issues 1st with network than with billing, when will you get it right? as it is I am sitting with a negative balance in my account due to your mistakes, I have a debit of the correct amount going off on the 20th and now another amount on the 01 July please can someone explain? what's worse is that Vodacom does not like reversals they credit the account but that does not help my negative bank account which they have caused, I am getting real tired of the service, but I am certain I will get an apology and asked the very same things I have already complaint or asked about in a week or so after all that's the extent of service one gets from Vodacom