have you used that credit card at a gas station.. ie: "pay at the pump"?
The reason being, in Las Vegas and recently in Salt Lake City, thieves are getting behind the touch pad screens of gas pumps and placing "cloning software" inside the pump face plates. This allows them to easily clone all the numbers and any pin #'s from the card you may have just used to purchase gas.
I now only pay cash or go inside the gas station and use ONLY my gasoline company card with the clerk on duty - never, never, never use a debit card!
If you google "gas station credit card theft", pages of info on this problem...dirty dogs!!!
Sorry to hear that happened to you