Okay last night i used a $25 american express giftcard that my dad gave me to use as a credit card for my iTunes account. I begin downloading games for my iPhone. I downloaded $34.96 worth of games when my gift card had only $15.75 + $5.05 credit. now it says "There is a billing problem with a previous purchase." the giftcard still has $9.68 on it and now it won't let me enter it. it says my sercurity code doesn't match but it does. It says i owe $24.98. If i buy a $25 iTunes card can i pay it off? I don't have a real credit card.