I agree, you may need an educational advocate.
He had another sub in the mainstream room.
Boy, does that sound familiar. difficult child was nearly kicked out of daycare many moons ago, when he was acting up. I found out that he'd had a new "teacher" every 4 days or so. The turnover was horrific. No one knew how to handle the terrible twos and threes. (And it turned out they weren't real teachers, after all.)
I worried about how long it would take him to calm down at home. Weeks? A year?
One day. He was an angel.
Consistency is SO important!
I feel for you and him.