Inaccessible service

I have been trying to cancel my Vodacom contracts that I no longer need. After visiting a dealer I was informed that is only possible by phoning customer care which inter transferred me to another department. Now as these contracts are data contracts I do not know the number and thus had to rely on the person on the other side of the phone to know what I'm talking about and which contract I want to cancel. Well this did not work as the wrong contract was canceled and now getting the contact back on line is like giving birth, painful. It is easy to get a contract but getting it canceled is another story. I want to know why one cannot cancel a contract at an agency. They have access to the system and making sure that the right contract gets cancel will be easier for everything is done in person. I need help inaccessible