Maybe EA thinks you can easily find them anywhere, I have to move 30 km just to buy an ea card at my nearest gamestop, online stores are always out of stock. This mean of payment is so unconfortable, has region restriction, it's really frustrating. It really depends where you live, for some maybe is easy to get.
Anyway such a struggle just to pay....Really EA?
It isn't EA's fault you bank using a diffeent type of debit card than everyother bank I can think of. I can't speak in 100% certainty about outside the USA, but here debit cards have the same 16 didgits as credit cards cince they are issued by visa or mastercard.
Best advice I can give is setup a paypal if you are having that much difficulty finding a way to purchase a digital card and/or stores are too far away to drive to buy a physical one.