The Better Business Bureau charges naive small business people for a sticker saying they're in the BBB. They are not IMHO a reputable place to go if you want to resolve a complaint, as opposed to just waste time and gripe. If you want an objective referee of a legal claim, consult a lawyer and go to court. Not the BBB.

Whether or not you are entitled to win a court case or should file a lawsuit against UA...I have no clue. That's what lawyers are for. These fine folks go to school for a LONG time to learn this stuff. It sounds like you were treated badly, but I'm not there on the ground. Ask a lawyer or let it go. If $850 is the worst unexpected expense to hit you in life, you are a lucky individual indeed. Personally, I never advise anyone to travel who doesn't have $2,500 in emergency funds behind them.