I'm being harassed by Discovery Insure

I'm being harassed by Discovery Insure. I'm getting SEVERAL calls per day. At first I ignored them but they kept coming. Then I started declining them and they kept coming. Then after about 4 years I decided to start answering the calls in order to tell them to remove my number from all their call lists, but when I answer they hang up immediately. I'm not sure if this is some sort of system they have in lace for agents to hit their targets but I am losing my mind. The calls even come through after working hours and on weekends. It's a frustration. And blocking the number doesn't help because the calls come from different numbers.

FIX YOUR SYSTEM