I'm probably one of the only people here who doesn't think the idea of suing someone for false advertisement is a tad absurd or even silly. Saying this is the very last time this performer will be on stage to that extent and charging fans hundreds of dollars for a farewell show that isn't really the last is stealing and again, false advertisement. It's not like an infomercial that says "Drink this for two and a half days and you will look like Angelina Jolie", it's common sense that tells you it's not true, and there is usually fine print or some type of contract that comes along with it. I sincerely doubt there was any fine print in regards to this show. [Unless maybe it was the very last show this week/month/year.]
She/whomever is in charged lied, they should pay the price.