I experienced once a similar situation.
K-mart was selling framed pictures with one of my wolf images. They purchased them from a high-volume framing factory, who unknowingly bought unauthorized / stolen images from a shady print salesman. First, I wrote a letter to K-mart about the unauthorized image use, who referred me to the framing factory and then I met with the factory owner who was very cordial and quite embarrassed by that situation, so we were able to work out a deal in a civilized manner without involving any lawyers to compensate me, let K-mart sell the remaining pictures, and the factory was able to keep K-mart as their customer.