insurance robo call spam

This company (phone solicit) called me on my cell to sell car insurance. When I pushed the button to talk to someone to have her take me off her list she hung-up on me. I called back and asked to speak with a supervisor and told why and the new person told me to Stop calling them and hung up

I get probably 20-25 calls per day at my business from 636-923-8263.  This has been going on for over 2 months now and it's unreal.  Does anyone have a suggestion as how to stop this?  I was calling the number back and THEY BLOCKED MY NUMBER.  They are messing with me now. They think it's funny that its pissing me off I guess.  I want to strangle someone at this point.

Recieved two calls from this number today, back to back.Curious to see who was calling me. I dont answer any number unless your on my contact list. Thankyou people for the info. Now I know what to exspect when I do answer.

I don't answer unknown callers normally, but inadvertently did on this one.  There was no response on the other end until I said "Hello?", at which time they hung up.