Vodacom - No joy in cancelling contracts

For the last 5 months I have tried to cancel two contracts at Vodacom Cresta. Each time I am told the cancellation has taken place and at the end of each month I am billed again. I feel that Vodacom should reimburse me for the 5 months where they have continually charged me. As already mentioned I have escalated this to the Cresta branch and have spoken to the Customer care telephonically, every month, but to no avail. How many times must I beg and plead for these two contracts to be cancelled? Vodacom, do you think this is actually satisfactory service? I would like this issue resolved immediately otherwise I will begin legal proceedings against Vodacom. I will not drop this!