what other mediation sites can the player use?
Any player with a dispute can choose any mediator they want. As far as this player, the matter is closed. He doesnt get to hop from mediator to mediator hoping he finds one that rules in his favor. We spent a month working with this mediator, including countless hours spent researching and providing documentation of his fraud. If he didn't trust this mediator, he shouldve went with someone else. Obviously he wasnt going to choose askgamblers, as they ruled against him previously, as well. These mediators do not make it easy on us. They exist to advocate for players. In this case, we had ample evidence to show abuse. If we didn't, the account wouldnt have been shut down, to begin with. This matter is closed.
It appears that you are quite eager to close this matter, which is understandable. In the interest of the community and for the benefit of your other clients, why not share the evidence you have regarding the OP's cheating, both for arbitrage and creating multiple accounts? The OP has requested this action, and it would demonstrate your transparency and honesty while clarifying who is truly responsible in this situation.