Barnes & Noble Barnes and Noble, Nook Books On-Line Purchasing Gift Card Scam Internet

I loaded my Nook Book on-line purchasing account with $150 in Barnes & Noble gift cards.  However, when I tried to make my first purchase - only $10 - I was refused because I didn't have a credit card on file.  Nowhere on their website could I find a notice that it would be impossible to use a gift card if I didn't have a credit card.  I've twice asked their customer service department to show me where it says this and twice they've been unable or unwilling to do so though they direct me to their "Payment Options" information page which does not address the question.  Meanwhile, I'm out the $150 and now I can't take the gift cards to the local B&N store.  Lots of apologies - no solutions.