I agree, I have found most of these organizations unable even to provide advice on how to obtain legal help. I understand that they are overwhelmed by the broad attack on trans rights and interested in taking only the most important cases. But they should at least be giving people who contact them a resource guide to finding help / helping oneself.
If you are low income, you may try contacting a local legal aid organization. Depending on where you are, they may be better prepared to represent you or at least to give you advice. Keep in mind, too, that the more work you can do on your own, the more likely your case will be taken, because it represents less work for them.
Another easily overlooked resource is other local trans people. I have a friend who has won appeal after appeal against her insurance company, and she was instrumental in my own success against an insurance denial.
Most of all, refuse to go away, document everything, and make sure you have a strong emotional support network to deal with any setbacks. A major part of the insurance model is discourage people, as that represents a victory by default for them. You may not win every fight, but advocating for yourself, being loud, and persisting are often sadly necessary for getting care even in states that mandate gender nondiscrimination.
