I would be very surprised if Guest Relations would give you documentation like that. It states very clearly on the back of the ticket that their tickets are non-transferable, so they're not going to help you get your money back after you broke their rule.
Another thing you need to consider about buying tickets from E-Bay: if the original owner used the ticket - even one day on a seven day pass - you won't be able to use it. When you enter a park, Disney uses a scanner to tie the user's finger measurement to the pass, so no one else will be able to use it.
Buying tickets on Ebay is a major gamble. You could get lucky and get a reputable seller, or you could get scammed out of hundreds of dollars. And then still have to buy tickets, on top of that.