How do you cancel a contract?????

Last week I emailed Cell C to tell them to cancel my contract on its expiry date as I want to move to prepaid. Here are the emails between them and me since then:<br> Thalitha Mavimbela:<br> Good day<br> Hope all is well. We've tried calling you but no response. We received your request to cancel however we need 30days notice.<br> Since your contract expires on 18/11/2015 you need to contact us on 18/10/2015.<br> Contact Retentions on 084 143 opt 2 Mon - Fri, 8am to 8pm.<br> Regards<br> Thalitha<br> Myself:<br> If my contract expires on 18/11/2015, I'm giving you notice NOW that I want it terminated on 18/11/2015, I don't see why I must let you know on 18/10/2015!<br> Regards,<br> Phillip Gonsalves<br> Thalitha Mavimbela:<br> It's a process your contract has 3months remaining we can't cancel now, if you don't call contract will continue on a month to month basis. (Note there is no longer \Regards"or any such nicety).<br> Myself:<br> I don't want to cancel now"