I just recently got a "pay as you go" cell phone from Walmart after getting advice from Freepers. I got it home, took it out of the box, stored away my receipt and threw away the box. A week later, almost to the hour, it died. Just died.
I called the company and they said exchange it at Walmart. Walmart said they wouldn't exchange it without the box!!!
Well, no one had told me I had to have the box to exchange it and I kept saying so and saying so till finally I guess they got tired of me, because they finally figured out a way to exchange it. I got the new one home, called Virgin and they assigned my number to the new one and I was fine. But this time, I kept the receipt and the box!
You should have bought a thousand of them, just for fun.
I've run in to this type of problem before and have a solution that has never failed me. I simply tell the clerk that they can have the box and packing materials the replacement unit comes in since I don't need them.