Have they done anything else?

Received a voicemail from a woman in this organization Monday threatening as with the others above.  I then received a call this morning from a man while I was walking into a meeting.  I explained I have no idea what he's talking about and I can't talk I'm at work.  He told me it might be fraud and I needed to speak to his boss.  I said again I can't talk I'm at work and he started yelling at me.  I hung up, he called back immediately, I hung up on him again.  Now my teenage kids are telling me he called and left voicemails for them this morning saying I have 24 hours to call him back or I would be served.  I guess it's time to get my attorney on them.  Be careful.