Say one thing do another

I requested that my contract which has prescribed be cancelled..I then had some consultant phone me and convince me to not cancel as she would give me more value for the same money as Vodacom did not want to lose my account. I agreed and now see that what she promised me has not been added to my account, only part of the agreement has been met. I now want the contract cancelled as I have utilised nothing as I am not in the country and don't even have the number with me.. Cancel my contract immediately. I have notified you in writing now. I want the number converted to prepaid as per my original request.