debit card fraud

The store wasn't happy refunding what i was led to believe was an ipod but as i hadnt left the shop they took my card back to cancel it on the till. however this must have been a bogus till cancellation and im now $141 out of pocket as no money has been returned to my account. I dont even have a product!! Such a dodgy shop, they advertise the real products in the window and sell you fakes. My friend got swindeled in this store too and when she complained they threatned to take $100 as they had her card details!!