I received a call stating a problem with my Windows.  I thanked the person and said I would take care of it and hung up.  He called back and started yelling and me.  A couple of days later he called with the same message and my wife answered.  She asked him not to call again.  He immediately called back and harassed her.  She hung up and then the following week he called again.  She told him she had reported his number to the FTC and asked that he not call.  He then called back with an unknown number and was confrontational.