And is it also so hard to at least post the thread YOU created a couple hours ago.
Rather then adding NOTHING to the topic?
I hate actually searching for a stuff, only to have to scroll through countless threads of people saying "geez didn't you search, this has been covered a million times."
Now to answer the Q. When I got my bumper or Apple stuff in general I never get receipts. I always just have them email it to me. If they asked for your email then the receipt should've been delivered to you in that manner, same goes for having it retrieved. Either way I'm sure they'll tie it to your phone say bring bumper in with phone and they'll verify the refund that way. Receipt or not.
My understanding is that they can look up past purchases using your credit card (which is what they did for me when I had to return something w/out a receipt one time because the guy at the Apple store may have input my email in wrong and I didn't notice). Kind of the way they tracked iPad sales via credit card to make sure you didn't buy more than two. Unless you paid in cash, of course.