Have you ever spoken to your states Dept. Of Education? They are the ones who can and will help you. The district is one Good Ole Boys club. The Dept. Of Ed is the boss of every school district.
The DPI will tell you the name and phone number of your FREE advocate. There is no cost to hire or retain one. I had one for my son. We got a lot done with an advocate next to us at the table. The advocates can take school districts to court.
The District can also investigate your sons case and insist that the school district take specific action. Or they can punish the district, i was told, by, say, withholding funding.
Dont expect the school districts leaders to go against one another. You need to reach above them.