Tough break! If it makes you feel any better, I'm sure that many famous and fabulous actors have had the same rant many times over. So often talent makes so much less impact than does the directors mental image of who should play a part. Your attitude in stepping back though may be what gets remembered out of all of this. Don't know if you remember the movie "The Big Chill", but Kevin Costner was the guy who commited suicide, and we never saw. He was supposed to be in many scenes, but they were all cut. He had such a good attitude about it that the director cast him in his very next film (Silverado) and you know where his carear went from there.
Wishing you a great experience even if it is not what you expected