Impossible to stop a Contract

I have been trying for many months now to cancel a 3G contract tyat came to an end a few years ago. I am therefore no longer tied in. It's impossible to do it in a Brach who give a number to call. Firstly no-one ever answers and when they do, they try to convince one to stay or offer other deals. When declined they say that a Text will be sent with confirmation that never arrives. I'm still trying to close my account with no joy. Please will someone from Vodacom contact me ASAP.