I was playing on BBO Monday night and my partner and I reached a game contract after partner had passed in 1st or 2nd seat. Upon seeing that my partner (dummy) had 11 HCP and a singleton, opponents asked for a redeal. We asked why before refusing a redeal, but then the host (opponent) redealt the hand anyway. Their explanation was that my partner had made an "unallowed pass" and advised us to "learn the rules of bridge" without providing any references. What would be the best educational way to deal with a situation like this, other than simply refusing to play with them?