Yes, find another trainer. I work with a lot of rescue horses. I actually really enjoy working with horses that decided that people didn't offer them a good deal. Once you get the trust with this horse, they will do anything for you. Most of my horses were free or close to it because they had been through the long run of trainers and titled "worthless".
I had a horse in a few months ago with a bucking problem. He had people on his back before, but had thrown several off and sent one to surgery. Other trainers gave up on him. A bucking horse is always trying to tell you something, whether it has to do with pain, confusion, or just not trusting, you just have to understand what it is. The fun thing about problem horses is that it is not like starting a new colt, you are actually starting below zero, cleaning up someone elses mistakes before even getting the chance to build correct habits. They don't follow the regular program and you usually have to listen to them and develop what they are lacking as you go along. They have to do these things until they own them to transfer them to other people and have the patience to deal with people that may just be figuring it out.
I know a lot of trainers that can do a good job bringing up a colt and starting it under saddle, but many of them scratch their heads and say its not worth their time to work with a problem horse. Really, I can see where its not worth their time for someone whose money depends on the rather rapid performance rate of their horses. Find someone that will take their time with her, you may end up waiting a little longer to get her back, but she is obviously not going to accept the norm.