taking money with no authority

i was with affinity for 3 months, and send them a cancellation email, as they requested i do, dated 06 July, guess what, they are still deducting the money from my account, every time i asked them why, they come with all kinds of questions , when i ask them to repay my money, they don't reply anything back, i am not using them anymore, so please make sure before you join them