A little buddy horse could be a big help in bringing her around. I've had luck with really anti-people horses in finding a job, usually herding something around while leading them. It could be a dog, chickens, other horses, etc. just something where you are enthusiastic and they can get proud of whatever it is and praised for it.

If you feel frustrated or disappointed they can really pick up on that. Think about how even the wildest and most antisocial horses seem to be attracted to the happy innocence of children. No expectations for the horse there from the kids, the kids are just happy to be around them.

"It's really quite amazing what a horse will do for you, if he only understands what you want. 
And it it's also quite amazing what a horse will do to you if he doesn't." ~ Bill Dorrance