Didnt leave a message, but I called them from my work number. Got a recorded message saying they were calling to go over my Medicare benefits. Funny - I don't recall having Medicare! SCAM!
Get a call blocker.
For a land line a call blocker is an electronic box that plugs into the phone line between the phone and the wall. It also needs an electric outlet. For a smart phone a call blocker is an ap. It may come pre-installed on your phone or you can download a free on.
For an old-style simple cell phone ask your carrier. Or put the pest in your contacts list - I give mine the name "X" - and give them the ring tone "no ring" or "silence". That will send the calls to voicemail without disturbing you.