I recently discovered that Michelin has used a picture of mine in 10 different travel books.  (Chicago, NY, etc).  The picture is being used as an icon, on each of the pages where they list places to stay.  In some books, the picture has been used as many as 15 times, and as little as 9.

I have no EL sales from this picture.

When I contacted Istock to look into this, they wrote me a generic reply that they had been in contact with their "RESPECTED" client, and that no EL was necessary.

I've written back trying to find out at least how many times they downloaded the picture, and have yet to hear back.

Istock's agreement says the "content" can't be reproduced more than 500K times without an EL. It doesn't  specifically say the book has to published that many times.   If the book that has my picture in it 15 times is published just 33,334 times, that passes the 500K mark of reproducing the content.  

Istock is clearly backing their RESPECTED client, and the compliance inspector says the matter is closed.

I have no idea how many times my picture was bought, (Istock hasn't responded)  so who knows if they bought one copy and keep using the same download in all their books, which is obviously using it more than 500K times.

Any suggestions on where to go from here? Or am I just tilting at windmills because I'm not a RESPECTED photographer?