cancelling discovery

I just want know how long does one have to wait or what can a person do if no one is willing to assist with cancelling a policy with Discovery. Since the beginning of Oct I have been trying to remove my vitality cover from my policy but no one from discovery is willing to help. All I have been getting is calls of people want to 'new businsess' i.e new policy. Once I tell them that I am now actually looking to cancel my because of the run-around, they ask for my details and promise to call me back which they never do. The frustrating thing is that this duck-n-diving from all these agents has costed me 2 debit orders and seemingly this will go on forever even though I dont want the policy anymore since no one is willing to cancel my policy. Who can I escalate this to?