What you need is not an attorney that wants to prosecute necessarily - but rather one that will go in and sit down with the principal, counselor, teacher, and you and go back over the exact verbiage in the IEP. The attny needs to explain that if the above people do not follow the IEP, that they are violating XYZ law and will be held accountable..
I had this happen with Matt and a new principal - it seemed he was determined to rile Matt up at every opp. I could not tell if it was a power trip or he wanted Matt out of his school. He succeeded, unfortunately in expelling him. However, I did not bring an attny into the mix, which could have changed everything.
Good luck.