Okay, go under history, go to search, from the drop down bar select subscriptions, change the date to when you signed up, hit search. A list of any subscriptions will populate. Click details next to your active one from here. When the new page loads, scroll down to the bottom and hit cancel subscription. That should work.
Make sure you read the fine print when you sign up for something.. they always get you with the auto-renew. Not just here but lots of other websites too. Hope that helps!