Email from IP Echelon

I received an email from you about a movie that was downloaded with our IP address.  The email was from you and one from IP Echeoln and I wanted to make sure it is a legit email from you because I have never downloaded a movie from any web sites.  My husband and I live here alone and do not have children in the house.  My question is should I be worried and pay the 150.00 they are asking for?  It was done at 11:54 p.m. so I'm sure it was a hack even though my wifi is secure with a password.  I know your email, if real, said not to contact you but I am not sure what to do.  I don't want to give into a scam or if real pay for something I didn't do.  Any advice would be much appreciated.  Thank you!