Yes you can be billed, the merchant if he had your old card with an old expiration date, simply will make up a new experation date. It will go through.
What you need to do is simply dispute the credit card charge. This is done in writing, not via phone and the exact details appear on the back of your credit card statement. It'll tell you what info to send in and why you are disputing your charge
This must be done within a certain time period, I think it is 60 days after the charge appears on your statement.
The credit card company will immediately take the charge off your credit statement and investigate. The merchant than has to prove that charge is legit. If they don't do it in a certain amount of time, you win automatically.
If they can prove it, and how can they if they don't have the correct experiation date, (unless they guessed well), you'll win the dispute
Remember do it in writing, do NOT CALL, you can call but you must do it in writing to preserve your rights.

