Bummer if that is what happened. However, I'd be kinda curious to see what they had to say. Of course, you can always call Visa and have them stop the excess charges. Visa will likely ask you if you have contacted the merchant to work out the charge directly.

I kinda doubt direct theft. If they made a practice of this, they would get busted. Credit card thieves don't usually operate from fixed addresses. The assets could be attached if they were busted. Maybe they have some new employee who is dipping into the till, maybe Visa's computer burped. You might want to see what they have to say before possibly slandering a business who may be as innocent a victim as you are.