I went through the same thing with my past trainer. He was a great guy when I was off the horse (mainly to schmooze me to keep coming back for more), but when I was riding my horse he treated me like utter crap. Then would tell me, "You haven't spent enough money with me yet for me to give you the whole picture and pieces of the puzzle", well in any disapline, you need all the pieces to get the job done correctly. I took the abuse for a little bit, thinking maybe I was just in a learning curve, and wasn't understanding all the material that was being flung my way..., but, it just kept getting worse.
The best advice I could give you is to leave. Since my ordeal I've actually put my reining equipment and dreams up for a little while, because the whole situation really 'soured' me for lack of a better term. You need to enjoy what you and your horse are trying to accomplish. If you aren't then it's just not a good situation all around for you and your horse, and you are just encouraging your trainer to stay the same by continuing to go and pay.