Are you sure Exped is asking the receipt or is the the shop selling exped stuff you brought your problem to?
Try emailing Exped first and ask for an instruction to claim their 'lifetime'. Perhaps you can walk with their answer in e-mail again to a shop. I doubt Exped self really will persist in asking a receipt. Most certainly if you mention you got this advice from Outdoorsmagic. Better even say you will twitter your experiences with exped and you have a zillion followers.
I once had a broken optimus. I didn't even went to the shop, just mailed them and a friendly answer later all it took was some postage costs for returning the broken one and I got a freely repaired one (I also got in their answer the option to buy a new one for a really small price).
Same with Wechsel tents, I had a broken pole. Went first to shop (stupid ofcourse -> no warranty and such). thenI emailed them. few weeks later free new pole part in my post box
If you feel the product didn't meet your expectations you might expect form the information a manufacturer gives on his website. Just mail them. I found out that most of times the serious brands take your complaints very serious.