Buyer is Trying to Scam

Hello, so I was selling a Fortnite Llamalaxy code to a seller with no previous purchases or anything, and I had automatically delivered the code, and then 10 minutes later they said it has been used already, so I asked them if they could send proof that they didn’t redeem it and send a screenshot of their redemption history on Epic Games and if they did and it showed they didn’t use it, I would give them a new code, but they didn’t even answer me and they automatically put it on dispute with Gameflip, and I provided a ton of evidence already, it’s pretty obvious they got the code and are just trying to scam me to get their money back, so can any Gameflip employee please look into this for me? Order #: 9e35fb8a-7b24-4b3b-811d-89a02761dc08 My Code: YA19L2