SI Joint Fusion for disabled mother

I suffer from Ehlers Danlos Syndrome and a complication of that Syndrome, in my case, is my SI Joint. There is a Joint Fusion which means the difference between my walking and my being wheelchair bound. My insurance is Blue Cross Blue Shield, and despite having a policy provision that should approve this surgery, they are denying the surgery without cause. I've suffered for the last 7 years from this dysfunction. The pain is unrelenting most times. This has affected my entire life. I am in constant pain. I cannot walk normally and, often, cannot walk unassisted. I cannot go for long trips. I can not play actively with my child. I work full time but I cannot afford this surgery on my own and I am in desperate need of this fusion.  I am working with my company to work with our Plan Administrator but it doesn't look good. My only choice now is to try to raise the money for the surgery.