Do you know if it would work in the store.
Google is your friend.
Credit and debit cards
The most common method to add money to the "wallet" is to use a credit card or debit card. This payment system is available in all areas with PlayStation Store support. Visa and American Express gift cards can also be used to add funds to the wallet. Although select areas require that you use a credit card with a billing address from that specific country.
Nvm, didn't see the gift cards after the American Express. My bad. Thanks.
They work just say you have an American Express card and type the stuff in, mine worked for the MGO stuff