I recently bought an ipod online. I received a phone call from the merchant stating that they had a problem processing my credit card and they advised me to call VISA.
Called my bank, and they said that they put a hold on the order because they thought it was a fraudulent transaction. Now I shop online often, and that ipod barely cost $400. I asked why, but they gave me no real answer, something like ... for the security of your account etc etc. Now, i don't want to have to do this everytime i order something. Don't get me wrong, I like that VISA has this "feature", i just don't want to have people calling me everytime i make a purchase. If the merchant hadn't called me, i would have waited forever since VISA never advised me about the hold on my order.