Emergency Meeting, NOW. Not a week from now, two weeks from now, or three weeks from now. Tomorrow. That's what an emergency meeting is all about and this is what is needed.
I'm going out on a limb here, but I don't believe that every time your son has resorted to violence his BIP is not being followed. I'm afraid your son is learning a negative, but powerful, lesson here. He needs a change in placement fast and in a hurry.
Whether his escalation into physical violence is due to his BIP not being followed, his frustration that they are trying to get him to do what is unable to do, his inability to monitor his reactions, makes no never mind. They are not able to give him the support or the education that he needs and deserves. If this goes on much longer a very, very serious consequence could take place. Your son could learn (and is actually being taught now by your own admission) that violence gets him the goal he wants or a staff member at the school is going to file charges. He is absolutely, positively, unequivocally not getting what he needs and what he is guaranteed by law.
Place the call. Emergency meeting. Change of placement. Period.
My two cents.