They didn't reverse the decision until we got a lawyer who knew the ins and outs of the appeals process. Thankfully, we were able to work through that fast enough for treatment to be effective... there's no way we could have paid out of pocket.
The ability of an insurance company to unilaterally deny treatment, or determine what type of treatment a patient receives, is obscene and should be categorically illegal. There is no instance in which a medical bureaucrat should should be able to, sight-unseen, overrule a patient's own doctor.
It's so frustrating.