Scratched xbox gift card

My son had a Birthday party and received multiple gift cards. One of the children scratched the back too hard and partially removed the redeem code on a $25 xbox gift card. I have been chatting online with an Xbox representative and supervisor for over
an hour to no avail. We have the card in hand with serial number and can see the first eight characters of the redeem code. They will not help unless we have the receipt from the purchase of the card. There were 20 children at the party and he received multiple
xbox gift cards. I can't ask every parent for their receipts! Microsoft will not do anything without the receipt. I have the card in hand!!! Please help. This is very upsetting to my nine year old and to me, as that they will not offer any assistance.

:)