Vodacom delibirately deduct more money from my account than i owe them

I have been struggling since October for Vodacom to resolve an issue that I have logged with them.After nearly 40 phone calls they continue to escalate and no one comes back to me. I unfortunately upgraded my account with them to a new account for R999 a month, the first billing that I received reflected that the cost of the new account is R1100, Over and above this they also billed me for the previous contract as well. I phoned them before the debit order went through and they told me that it will be rectified before the debit date of the 25th of November. instead of paying the agreed R999 I was debited an amount in excess of R2200 and they continue to tell me that they have sent it their admin department for reversal.... but still I am left out of pocket. I have offered to come their offices to assist them in returning my money but they are adamant that the are capable of rectifying the issue.

I honestly wish that I never upgraded my account with them and that I rather joined a service provider who are ethical to the agreements with customers and who don't debit customers for funds which don't belong to them.