I have a credit card that was sold to another company a few years ago and I stopped using it. I never made a single transaction under the new company and they issued me a new card and number when the switch was made. In the month that the card expired the company sends me a letter saying they were going to cancel the card, and, right then, literally to the day, I get hit with 2 transactions in China totaling $600. I call the company, because isn't it obvious, and they roll back the transactions. Over the next few months both transactions are credited, both times I have to call the company, and both times they offer me a check for the credit balance.
I have on idea how that card got used. It, literally, never made it into circulation, ever, from me.