Here's what I think.
You have an attitude. An attitude born out of being spoiled and getting whatever you want. Your entire opening posts reeks of aforementioned attitude. Wanting to take it further because he "breached the DPA" - do you even understand what the DPA is for?
If the school has a rule or the Head of Department doesn't wants phones in class then suck it up and put it away. Sure they could have shown a better attitude but that's just tough you should have just put the phone away.
What's the matter? Did the poor teacher who has to earn a living upset you?
Sorry if this sounds harsh but you need to pull the silver spoon out of your backside and start living in the real world.
I didnt have a problem with the way i was treated until he attempted to go through my iphone, clearly you missed the point i was trying to take, nice one you managed to echo what others have said whom all missed the point, nice ...