Someone is copying your work.

You found your photos on their site, your wording in their ads, or your product with a different label. It is infuriating, and the first instinct is to post about it everywhere.

Do not do that yet. The step that actually works is a formal letter that names the conduct, tells them to stop, and sets a deadline, all on the record.

Most people back down when they see you are serious and organised. A cease and desist letter is how you show that without escalating to a fight you did not want.