mobile no. — Mental harassment by calling and massaging

Sir someone with mobile no [protected] is creating problem. he keeps calling and massaging me. i dont know who is that person but please help me as soon as possibe. when i said him i will give complaint in police he said very bad words regarding police calling police like slaves and also abused them.
i changed cell no once due to that person but he managed to find my new no and again started trouble.