A couple of points:
- My wife works for a printing outfit and there is no way they can follow-up with every customer to determine if they have copyrights for every image submitted. She will check when the image looks professional (studio shots graphics, artwork, and the like) and ask for a release, but for candids and "regular" looking shots, a customer can claim whatever they want.
- Typically printing houses will cover themselves against errors/omissions/pain in the behind customers by sending out proofs for customer approval before they print anything. Regardless of who dropped what from where, the customer approved the final output, whether by actually doing it or implicitly authorizing the printer to go ahead and print as is.
- There is no excuse for failing to give credit where due - I had to rail against a local newspaper publisher for illegally taking images from my website to use in an advertisement thanking me for my work in a fundraising calendar. As crazy as that may sound (why beat on them for making a thank you ad for me), they
a) failed to ask for permission - I would have given them higher res images than the crappy, low res, low dpi web versions I put up
b) disregarded copyright law by assuming (and the publisher told me this herself) that because they were on the web it was OK to use them without permission, and
c) didn't think it was important to verify that a model release was available for the children photos they used in their ad.
In that situation, all I asked the publisher for was a letter stating they took the images without my authorization (just in case the parents came after me for the use of their kids' prints by a third party without their express consent) and agreeing in writing to train their staff in the basics of copyright law.
When I didn't get what I thought was a simple, reasonable request, I contacted the parent publisher and spoke to the head cheese, making it clear that I was dismayed that a newspaper publisher would not only blatantly steal images from a website, but also show complete disregard of the importance of copyright law, because after all, how could someone be promoted to the position of newspaper publisher without knowing something so simple
. Little did I know if was the guy's first day as the new head publisher and I was welcoming him to the job with a copyright violation issue
He said he would speak to her the next day, Tuesday and within 3 days the letter arrived in the mail.
So, as others have said - do not back down!
But you need to move fast!
The more you wait the more difficult it will become to remedy the situation. Find out who their boss or head agency is and go right for the top, kindly explaining that you're not looking for money, all you want is to be given credit for your work or that your work be removed from any and all promotional materials, whether already printed or not, and ask for it in writing.
Best of luck!