Money has no conscience IMO, these guys are quite happy to rip off folk, I would have no issue at all in taking the goods.
It happened to me once, I bought a game boy game in toysrus, £29.99, went to collect the game from the secure collection point, the guy serving looked at the receipt, disappeared, came back 5 mins later and handed me a game boy advanced and the game I just bought.
Thanks mate I said, walked out laughing.
No morals, no regrets, tough luck on them......