Bought Xbox 360 at Walmart. Missing parts!?

Yesterday I bought my boyfriend an xbox 360 (arcade edition). The box said it would come with the console, cords, wireless controller, silver membership (?) and memory card. We got home and the box had everything but the memory card and the membership live card. How can I prove to walmart that I did not receive the items? I'm not an untrustworthy person, but I know they don't know that. I just want what I paid for! Any advice?