I found a story of mine on Gather.com – copyright infringement. I am so glad you published your article.

I saw the response you received, which of, course, sounded like a run-around. I would like to be paid for my story on their site. I love your idea of invoicing. What shall I charge for a 600-word humor column? That’s what was filched.

Send them an invoice for $750 for the unauthorized publication of your copyrighted material. They will forward your complaint to the member who posted it and they will respond to you. If you can figure out who she/he is, you might be able to get them to pay up. Read this:
https://writersweekly.com/success_stories/004029_05022007.html