Son is worse after being released from prison - Anon

Hi. My son has just spent 18 months in a YOI ( young offenders institute ) and has now been home for just 9 weeks. Prison has not been constructive at all and he thinks he is some kind of gangster. He made 'new' friends in prison and has stayed in touch with them. They are a worse crowd than the pals he hung around with before he went to prison! What's all this rubbish about prison rehabilitating people? He was supposed to have been sent to prison to be rehabilitated according to the Judge and the Probation Service? My son is still on probation but that is a complete waste of time too! I am now at my wits end with him bringing trouble to my door and thought I would never say this but I am seriously considering kicking him out. I have tried and tried and tried to support him and talk sense in to him but as I said, since he has been in prison, he has gotten worse. Anonymous.