cant fulfil a simple change of bank details

Vodacom is incapable of simply changing the bank account details of a cell number from one business bank details to a new business bank details.<br> After being told that my request to do so had been completed and successful the monthly debit still came off the old account, whats more Vodacom then also debited the new bank account and not just for the cell number in question but the two other cell numbers that were coming off the old bank details. <br> After explaining this to them they now seem to refuse to reply to my mails. Real productive!<br> Im trying to get a refund for the double charge and to sort out a seemingly simple issue.