These people have no hearts. WHy should they right?

They contacted me regaurding a debt, yet when I told them to please stop calling they said they didn't have to and hung up on me.
I called back and said how rude they were. Then they proceeded to threaten me, said they knew where I worked, my mortgage agency, and that I should seek legal council and hung up.

They were rude, violated my privacy by calling my sister. And now harrass me when I told them to stop calling.