Phone confiscated at school parking after school hours what to do.

my school has confiscated my phone at the school parking, the phone was in my vehicle and i can prove that, but the school is not ready to listen to me. when my parents had gone to claim for it, they said they would give it after a year, is this legal? i mean, i was using it after school hours outside the school and they refuse to give it to me now, its already been 3 weeks without my phone and i feel so lost.. please help..