PSN accepts Visa credit cards, but not all Visa credit cards. PSN accepts some Visa debit cards, but not a lot of them. First of all, the billing address of the credit or debit card must match the state and country that you registered as where you live when you created your PSN account. If your billing address doesn't match where you said that you live when you created your PSN account, then you can't use the card. Also, if the card doesn't have a billing address (as with Visa gift cards), or your bank doesn't support the address verification protocol, then PSN won't accept your card then either.
So essentially what you are saying is that if I were to move to a new place then my card would no longer work because my new address is not the one I created my PSN account with? That's a horrible flaw In my opinion.