Declined 76561198053727976 ([k²] kuestif)

Victim:
|steamID: Space Cowboy V2
|steamID32: STEAM_0:0:48270736
|steamID64: http://steamcommunity.com/profiles/76561198056807200
|customURL:
|steamrepURL: http://steamrep.com/profiles/76561198056807200
Scammer:
|steamID: [k²] kuestif
|steamID32: STEAM_0:0:46731124
|steamID64: http://steamcommunity.com/profiles/76561198053727976
|customURL:
|steamrepURL: http://steamrep.com/profiles/76561198053727976

I was unaware that proof was needed as I have never reported anyone before. All I can provide is this link to his TF2 Backpack. There you will find an Earbud gifted by "Tikan". Clicking it will show that I was a recent trader with that bud.
http://www.tf2outpost.com/backpack/70524
So what happened was he was selling the bud at regular price, I bought it from him and after was when I realized that it was gifted and demanded a refund. I paid 24 keys. He gives me back 20 keys, but decides to keep the other 4 keys. He says "Expect a lot of bad people in the world", "Don't expect someone to hold your hand", "Thereare consequences for your actions", "f✿✿✿ off", etc.

Hello, it's your own responsibility if the items checked are gifted or not.

Not to mention you don't have any screenshot of the chats, rejecting.