Have you done a very very good virus scan on your computer(s) to verify you dont have a hidden virus capturing keystrokes?
last week i had my checking account compromised also. the only online orders i have ever made were from 3 ecig companies. I noticed that something was up when I had a charge from Valve Software for 89 dollars. Then I looked down and there was a charge from a music store in kentucky for 1300 dollars. I just looked around on the forums today and saw this. I dont want to point the blame towards a specific company, as said before it may be the people approving the cards, however it cant be ruled out. where were everyones fraudulent charges paid to? perhaps we all have had compromises paid to the same companies?
The Valve software people are a charge that shut down my first CC. I now use a prepaid card for my online purchases, but a CC I use for auto payments for utilities was just hit. So I honestly think it isn't related to the online suppliers.
If you have a VISA debit card, it is still governed by Visa guidelines.