Tek720... my advice...
Call nintendo support and ask them if you would ever need a receipt w/ serial. If you do... i've worked some retail... you should be able to get a copy of your receipt with the serial number, wether they get it via computer or they hand write you one it can be done.
Either way Tek720 you need to get proactive n get on the phone call nintendo figure it out. If u need the receipt you may need to get up on the ebgames manager and if he doesnt take u seriously get online find a coporate # and make a stink.. eventually you'll get what u need.