You got screwed by Best Buy. Welcome to the club. I got about $200 in gift cards for Best Buy from various people for Christmas several years back and pocketed them until I had a use. When I finally went to Best Buy, the barcode had faded enough (still visible, but barely) that their barcode scanner couldn't read it. I was out $200. They wouldn't do anything about it. The numbers below the barcode were still readable, but they said there was nothing they could do.
Two lessons learned: Never buy anyone gift cards and never do business with Best Buy. -- »will.mx
That you should have elevated to store manager. If the numbers were visible, they could have manually typed it in, like they do with credit cards that have the same problem.