Redeem iTunes Gift Card (virtual) on iPad mini.

Hello.

I got an iTunes Gift Card, and I have a problem redeeming it. The only link that the email with the gift card had was open in Passbook, and as you might know, they didn't put passbook on iPad mini (I know, ***). So I tried using the 16 letter pin, and redeem it through the iTunes store on my iPad, but for some reason it won't accept the pin (invalid validation number, blah, blah, blah...). My computer runs 10.5.8 mac os, and iTunes 10.6.3 is having some big problem (crashes on opening). So is there anyway to redeem the card using only the iPad, and without calling Apple or going to a store or anything that will rack my nerves, which, at the moment, is a lot of things.