Harassing calls

I saw reviews that said, "block their number" I have and they just call back from a different number. Threaten all kinds of stuff, arrest, repo my car, call my job. They even call on a Sunday when I'm pretty sure they aren't even open. I stopped answering calls with numbers I don't recognize. They don't leave a message if I don't answer so I look the number up. In the last week they have called 3 times and each time it's from a different number.