Airtel — My Airtel SIM card hacked

Address: Sorkha sector 115

I AM USING AIRTEL SIM CARD FROM LAST 4 YEARS APPROX...MY SIM NO IS [protected], SIM IS REGISTERED ON MY father NAME_veer_Pal_BUT ONE OF MY father RECEIVED SO my no to is abused my father MISCALLS FROM SAME NUMBER WHEN SHE WAS TRAVELLING WITH ME AND MY CELL WAS IN MY HAND..WHEN SHE MAKE CALL ON MY NUMBER SOMEONE RECEIVING HER CALL AND SAYING THIS IS MY NUMBER [protected]...BUT WHEN I TRIED CALL ON THAT NUMBER REPLY IS SWITCHD OFF or busy.now i am confused if someone hacked my cell number or just a fake...please help me