I have made some findings about this before if I remember correctly. There are people that have sued gambling sites before but the result has always been the gambling site winning the lawsuit. So just know that if anyone sue any reputed gambling site, the gambling site may win the case.
Yes, there was one story of a either a man or a woman, I can't remember the gender that sued the casino when they won the jackpot but the casino refused to give them their winnings because they claimed that their slot machine was faulty at that time. She took them to court and lost. She lost because the court ruled that the casino can cancel a person's winning if they won while the machine was faulty. In short it is difficult to win.