Im getting bullied

Im 150 cm (seriously) and i get bullied by kids my age who are 180 cm or something like that. Im the shortest person in my class and i get bullied for it. Today a guy from my class stole my phone and started to run away with it and i was trying to get it back for like 5 minutes. When i got it back he suddenly started to beat me up with his sleeve for another 5 minutes and this shit happens all the time. Is there something i can do about it? I tried to tell it to teachers but they don't give a fk.