We have the very same thing going on. A phone call made to threaten collections of on line web advertising. We have never heard of them before. They state that they have a recording of us agreeing to their services. They did send a hard copy bill to us. We live in Utah. The company address is in Nevada.
I am so glad I found this web site to find out it really is a scam! Thanks to everyone.
I am going to submit a letter to the Consumer Protection of Utah and the AG's office of Nevada. I will include a copy of the invoice to show mail fraud also.
Thanks!