Help! Does anyone know how to stop these "Windows technical support" calls?

“I’m calling for Microsoft. We’ve had a report from your internet service provider of serious virus problems from your computer.”
They call daily now, sometimes as early as 7am. I am on the do not call registry and Comcast block for anonymous. I’ve googled around and the best I’ve gotten is “just hang up”. I need to get rid of these creeps, once and for all. Anyone?—At first it was fun to mess with them, then I started getting mad and they get nasty!
~ Thank you!