I am in the process of chasing these users myself. Unfortunately, a good two thirds of them are Chinese, and I suspect I might as well just put my lips together and blow! I did have one success with a posh Parisian Chocolatier, who claimed that it had been shot by their own commissioned photographer. But when I supplied the evidence to them, they admitted my ownership, and confirmed that they would be having a quiet word with the freelance photographer who tried it on. Hope he lost the account!

Hello.
New to this forum. Hope you guys may be able to offer some advice.
I have contributed to an image library in uk. This agency has relationships and agreements with other agencies worldwide. I have been doing "reverse image search" for the images held on file at this library, and the other libraries which it has these agreements with. I have found approx 100 image uses that I have never received payment for. I have contacted some of the publications that have used my images, and a number have got back to say that they have indeed purchased a copyright licence, and named the library that they have purchased from. So I have tried to contact these libraries for confirmation of sale. None have replied! Totally ignored my contact. I am guessing one of three scenarios here. Either the user is spinning me a yarn and have not purchased a licence.Or, they have purchased a licence from one of the libraries with a relationship to the primary library, who has not passed on payment to them, and ultimately not to me. Or, they have purchased legitimately from one library, who then did pass payment to primary library, who then did not pass payment to me!
The two main libraries that seem to be cropping up on regular basis are "Corbis" and "Stockfood". And whereas I am in no position to accuse anybody of anything at the moment, I really need some answers from these two libraries, which they could quite likely supply, but are choosing to ignore my approaches.
Anybody got any suggestions?