Should not have used a Debit Card. You can go to your bank and
tell them that the transaction did not go through, and it should
not have been deducted. Email Blizz also.
Blizz doesn't take debit cards, I think when you put in your
debit card number, the site send a query to check and prolly
something went wrong there.
Just wait for Blizz's email, and maybe consider buying the
2-month card instead from retail stores. Comics connection or
random game shops. It's fixed at 50 bucks.