I enlisted the help of the ht. Apparetly I can send them to another teacher if they continue causing problems post red spot. She also said to give up on the idea of removing them from the carpet. On a related note apparently some of the parents have rung up to say that I'm 'too scary'. I know I was a bit shouty last week, I was just so stressed. Hopefully plugging away with the behaviour system will reap rewards in the end. The ht's been constructive about it so think I've got her support.