Each one of these people needs to die, or at the very least get the living shit kicked out of them. Sometimes we are too much of a hippie fuck community to just slap a mother fucker stupid, but after a certain amount of times being fucked over, one will reach their boiling point. I myself am guilty of being too nice after a show, and letting it slide until I see them next, but after countless times, I refuse to take it any more. From this day forth, if I can control myself from physically hurting them, I will try my best to ruin their reputation at the least. People like this need to be exiled from the scene and not allowed to trick anyone else into their deceit. Now if I'm actually really close friends with the person, then usually I will give them the benefit of the doubt, and a grace period, but after a few months, it can ruin a friendship.
This is how we make money, and we probably turned down another gig to play at your show. I know it sucks to lose money, but that is part of this game. It is a high stakes gamble, and very rarely turns a high reward. It takes a certain drive and passion to have the patience to learn from mistakes, and stick with it through the heartbreak. You need to know from the start that you may lose a shit load of loot, and you need to be OK with it. I have lost so much money in this game you'd wonder why I even keep doing it, but I have also been very successful over time. Don't get it twisted, I still lose money regularly, but I never go into a situation without having enough money to recover or pay the talent.
If you do not have enough money in the bank, and on hand in envelopes to cover the cost, then you should not throw an event. Too many promoters anticipate a certain amount of money to be made at the door so they can use that cash to pay artists, but that is a terrible way to do business. The fact of the matter is that the majority of parties are a financial failure. My personal estimate is that only 20-30 percent of events turn out to be profitable, so you are a dip shit if you don't plan ahead.