iTunes purchases

This has been happening to me every month or so. I do not know how, I do not play candy crush, neither does anyone in my home. I do have a cc in my iTunes but I have never bought anything but extra storage. i got an email from my cc for suspisious activity. The iTunes activity which is at $150 or more for this month maybe last month too on iTunes! Who does that? Not me I could NEVER afford that. Please help me either way you can.