Missing my sister!

Ive receantly just moved to Buffalo NY from Gastonia NC and i left because my dad was abusive towards me, I now stay with my mom and everytime I try to call my sister he never lets them answer or he'll turn his cell phone off. Since ive been here he has changed their house number and turns his cell phone off when I call. What should I do?? Im really sad and keep crying im 17 and my sisters are 14 and 8. I love them so much :( but i cant talk to them....oh and to make matters worst my lil sis bday just passed and i was unable to hear from her and see if she got my gift I sent!!