You can report things here:
https://support.chess.com/customer/portal/emails/new
I would hold off on reporting someone for what youre describing, simply because you dont know the circumstances.
Report a player
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Hi,
I got a message from a new member by the handle Edith Allard, who I haven't played. It's an email scam.
Martin
Hi there. I would like to report a player. I was playing a 30 min rapid rated match, I was white and these were the moves: 1. d4 Nf6 2. c4...... and after making only one move my opponent stopped playing. He didn't disconnect or anything but after about 15 minutes it said I won by Abandonment. That's all well and good, but I would like to report this player as I don't believe such behaviour should be left uncensured. I took screenshots of the match with about 25 minutes on his clock left (I had used only seconds) and at about the 17 minute mark proving that the position had not changed one iota from my second move. How do I report this player? Alternatively, can someone explain to me what happens to players who do this exactly? I would hate to go on not knowing whether this kind of behaviour is tolerated or not.