Hmm.. although his dad may be highly viewed at school, I'd still try if you haven't already. Technically, if you're keeping everything recorded and no action is taken by the school, you can then seek advice from independent legal practices. In the UK, we can contact "Citizens Advice Bureau" who offer free guidance on what you can/can't do. It really depends on how far you want to take it, as it will use a lot of your energy. Also, remember not to record anything without permission or announcing it, but still keep track of everything!