you said DEBIT card, not CREDIT card, try to never use a debit card when you dont know who you buy from (like use it only at a walmart or grocery)
You can stop payment on your CC, or argue a purchase, or have it reversed, but w/ your Debit, I think youve just given someone access to your bank account. Its connected directly to your money, not the banks "money" as an inbetween stop.
(at least thats how I understand a debit card works), you might want to call your bank or go talk w/ them to see what you can do to get your money back. st