I seem to get these types of calls about the same time every year.  This is a scam.  I like to have a little fun with them.  When they told me they were going to contact my human resource department, I gave them the number and said go ahead, when they said they were going to be at my house that night to serve me, I told them to send someone cute and I would open the door naked.  I have to say it is pretty fun to get them all worked up while you (the one being harrassed) is calm.  I have them hanging up on me most of the time.  After awhile the calls stop...then the next year it all starts again.