I recently received a message on my Xbox that contained a redemption code for a $15 Xbox Marketplace credit that I earned from making my first marketplace purchase on Xbox One. I did not redeem the code for quite some time, as I was leaving it for when I wanted to make a purchase. I decided today I'd go ahead a redeem it so I could buy the Titanfall maps that come out tomorrow, but now the message with the code has disappeared from my inbox (likely because of the 30-day delete cycle). I haven't been able to retrieve it on the console, the website, or the app. How can I get this code recovered?
I just got off the phone with Xbox Support and they said to direct my question here.