There is something you can do, however.
I have practiced law for some time, and no, you cannot, easily at least, twist their arm until they stop. You can, however, bring your comics to the region they are sold in(which is still a painful and elaborate process) thus causing tension in the higher-ups of that crummy bootleg company... If your characters and comic is licensed. If not, then there's nothing you can do except tell people about them.
That being said, the process of eventually getting to the point where you can pin them against the wall is very tedious and disquieting, and possibly not worth the effort. It all depends on what exactly your comics mean to you.