as I said before I don't think he is lying by the proof of shot we have seen so far he bought from someone at TG channel that you send him so the responsibility is on you
and as I said you can give game seller paid for to resolve this so yeah send him game resolve your case and look to see who was the scammer in the channel.
so yeah last 24h to send the game to the buyer or Refund him. as it is pointless even if you find the one who did scam at your channel. unless he is MPGH member as well.