I say keep bugging your dean until he threatens to get you in trouble
But this is serious, I had a lot of stuff stolen from me in my school gym changeroom. Money, a nice bag
a t-shirt...and my friends lost a lot of things as well, a ps2 controller, lol. money, cd player, mp3, um...a t-shirt...again lol
If i were you, i would keep bugging the dean to do something about it. And i would keep my eyes open and make people you know be aware of what is lost.
Your phone should be really easy to find, if someone is making calls from it. Call the company, get the numbers he's calling. Search the numbers on the internet, you can find a last name, an adress...may be help.