I had a similar problem, bought a 50 buck gift card and used it to buy a bunch of books, they charged the gift card but kept the books then told me there was no way to check the gift card for said purchases. This happened around Christmas. I spent a couple weeks writing emails, complaining, before the emails found themselves in the hands of a tier three cust. service rep. They told me they had been having this problem and asked me to create a new account and they would transfer my old stuff onto it, since then I've had no problems.
Hope they pick up the pace on your issue, it took almost three weeks or so for them to come to some conclusion with me.