[senco-forum] downward spiral in school behaviour, primary

Our school has always had a number of children with quite severe BESD and challenging behaviour. We have a whole school behaviour policy which uses a stepped approach and classes have their own variants on golden time. Those few children (several with statements) for whom this is inappropriate have additional reward strategies and small group/1:1 work. Despite this, at times these few display more extreme behaviours, such as running out of school, climbing trees, swearing at staff, refusing to come off the playground, repeatedly attacking other children. Various agencies are involved and each child has an IEP and strategies in place to manage as best we can in a mainstream context. Unfortunately we have increasingly occasion to resort to short term exclusions. We have instigated a short period (11/2 hours of working with a member of SMT on return from an exclusion to try and reduce the "Hey look at me , I had the day off yesterday" syndrome
However in recent weeks the extreme behaviour of these few seems to be impacting more on each other and on the next group down (all of whom have BESD, but previously have not displayed such extreme behaviour)
One child summed it up today. "No I'm not ***** going to, and you cant make me, all you can do is send me home, and then I can play on my play station, so *** you"
I can see a worrying downward spiral......any ideas you wise people at there?
Kate