If you take a single card out of the deck randomly, the odds of Let it Ride do not change. This would be true of any casino game I can think of, where the cards are shuffled between hands. Without knowing the missing card, the effects of removal of bad cards and good cards exactly cancel one another out. So, complaining is not mathematically justified. Even if they found that it was a high card that got lost, it was still accidental. It could have just as easily been a low card that got lost. If it happened to me, I would have let it slide. I think an apology from somebody would be called for, but they probably didn’t want to, lest it give you more bargaining power if you did make a big scene over it.