Cancellation of Contract

I have been in contact with Vodacom over the last 10 days trying to cancel my contract. I was given a quotation which I paid in order to do premature cancellation, and I sent it through to cancellations department together with a copy of my ID and the forms. I have subsequently phone every day since then and each consultant assures me that they will load the cancellation after which 24hours pass and it STILL isn't done. I call the next day, and they say again they will load it. WHY? Is there no record kept on the system? I need my contract cancelled with immediate effect and my number to be prepaid...its easy for Vodacom to take my money but then not follow through with their promises, it is unacceptable.