My son's teacher withheld lunch from him till the end of the school day , what can i do about it?

I have an 11yr. old son who is in a small clroom for having behavioral issues and on Tuesday the teacher withheld lunch from him for ripping up his schoolwork, and then gave him his lunch at the end of the school day now the food has been sitting for over an hour and now it was cold so he couldn't eat it, what can i do