I do photography as a hobby. When I reach the point where I wish to complain about unauthorized use of copyright images I do not want "credit", or images to be removed, I want damages. For some reason people think credit is sufficient to excuse bad behaviour, and removing images after they've profited from them with no additional recourse is fine.

It rarely comes to the point of making a claim, just when people blatently copy images and pretend to have authored them, or when companies are printing them and selling them on media, t-shirts, etc.

But generally the process is pretty smooth from a "complaining" side. Certainly by the point a first letter has been issued without any reaction the next step is to give up, or start complaining "upstream", or via other media/mediums.