REFUSAL TO CANCEL MEMBERSHIP (VITALITY)

i have just called Discovery wanting to cancel my Vitality Membership Card with them because I don't use it despite the fact that they deduct money from my salary every month and I don't even know how to use it. The lady I spoke to asked me a number of security questions which I answered to the best of my ability. One of the questions was what colour is my vitality status or something to that effect . I told her I do not know because I do not even know what that means. The other question was my home telephone No to which I rep**** I no longer remember it because it was long discontinued. She told me she could not cancel my membership because I had failed to answer her security questions. Really ??? What am I supposed to say if and when they ask me questions that I don't have answers for?? Now that means they are going to continue taking my money by force just because I failed some stupid security questions, questions I was never asked before I took the membership ?? I want that thing cancelled and I want it cancelled like yesterday!! Why must I be forced to continue paying for something that is not beneficial to me ?