Harrassing phone calls

This is getting ridiculous, I can not even answer my phone, as soon as I think they have stopped after 4 years I am still getting these harassing phone calls. they claim if I don't contact them they will have to arrest me , also they will have to send the proper authorities. They called on a no phone number after they could not get a hold of me . They are getting ridiculous.  I want to know how to get rid of them I keep blocking every number they still find a way. They are breaking the law to say they will have to arrest, call the proper authorities and take action to have me arrested.