There has to be a way to fight back. Maybe one could sue an arbitrator for not being impartial. I imagine that arbitrators are indemnified, but I can't imagine that indemnity extends to fraud. If anyone could successfully sue the arbitrator or their firm for fraud, then that precedent would surely make arbitrators a lot less comfortable acting on behalf of companies that hire them. This is a money game, and money is the only way it's going to get solved. It has to be less lucrative to behave badly than to behave fairly for anything to change.
Surely, but it won't be easy. As far as I know the Federal Arbitration Act provides practically no oversight of arbitrators, and instead just exists to make whatever trash said arbitrator puts on a slip of paper is legally binding, so we must then look to case law, but in the supreme court instances the rulings have consistently ruled in favor of unbreakable waivers of rights to trial.