Mediacom did this
Our local cable company, Mediacom, did this. I had my cable internet shut off several times . When I finally went in in person to find out what the hell, it turned out A) they had been sending the "copyright violation notices" to the wong address (mistyping it every time) and b) the ip address not only had never been assigned for me (dynamic dns kept a log of what IP I had), it was for a town hundreds of miles away! I cancelled service on the spot and got DSL.