Is there a way to report a player outside of post-game screen?

I need to report a player who's adding people, asking for gift-for-gift trades, and unfriending as soon as they get their gift (before reciprocating).

I accept that I was an idiot and got screwed out of that RP. I don't care about getting it back. All I wanna do is make sure this player faces punishment for scamming people.

Edit: I didn't add someone promising gift-for-gift trades. I added someone I had a good game with, even played more games with them throughout the week. They just pulled this shit today.