Bad Service - Mweb

Been trying from November 2014 to cancel my contract with Mweb. They keep on saying I should register on their website to be able to cancel my contract but if you go to the website you need to buy other data bundles or something to register, I told them last year I do not want to buy something else I just want to cancel, the e-mail they send said I should write a letter and sign and submit with a copy of my I.D which I did and is still battling to cancel my contract. My contract did expire last year and in now on a month to month basis and they do not want to cancel this. Why is it such a mission to get this cancelled.