ruserious,
Do you really care about getting a warning letter from a bunch of troglodytes of which NOBODY has any respect for? Here, a warning letter should be looked upon as a motivational tool to look for someone better to work for, it actually probably a good thing.
The damage was done a few years ago, its just become serious now. Sadly they have repeated the mistakes of GF and those in high levels will go down in history as killing what could have been the best company in the world to work for. As has been said before, its their train set.
You can't take them seriously any more. Once you realize that then its much easier to deal with the lunacy. Carry your resignation letter with you, leave the date blank and fill it in when the situation arises. Selling out your self respect and dignity goes with you to the grave...the job can be replaced in a few weeks.