A couple of months ago, they ran a promotion for movie ticket vouchers. It was a crappy movie, but I had a ton of UPC's, so I sent off for 12 tickets (plus $1.99 S&H for each one) so I could take everyone out to the movies. The vouchers arrived just fine, but they didn't work because there are no participating theaters in my town. They could've just said "Tough luck" like some other people have in the past or told me to pick something else, but they actually went out of their way to help me out. One of the owners of Langer spoke with the movie ticket people and came up with a deal and said they would send me a check once I e-mailed the codes to them (so they could be canceled out). I thought they would probably just refund my postage or, at best, maybe refund the juice. Not only did they do that, they also sent me the value of the movie tickets. I can't remember the exact value, but the check was for something like $168.
Now, obviously, my situation isn't the same as someone sending in UPC's and not getting a PSN card, but my point is that they were extremely friendly and did what they could to make sure I was satisfied. And I didn't even ask for them to go that far; I told them that I'd be happy with just getting some t-shirts and DVD's and maybe a coupon or something. I've already been a loyal customer of theirs, but that really cemented things for me.
I don't think people should expect checks or anything like that of course, but I think that anybody who sends in and misses the cut-off will be offered some sort of compensation in the form of a different prize. Or at the very least, I'm sure they'd be happy to send the UPC's back so people can use them at a later time. They're also likely to give out free juice coupons. I don't know how big the company actually is, but the guys running it are totally cool and they want their customers to be happy. I had a similar positive customer service experience with Shirt Punch, but that's a completely different discussion.