Legal Question in Wills and Trusts in California

If you are the rights holder, you have the right to sue them for copyright infringement. Have an attorney send them a letter demanding a monetary settlement, an accounting of all reproductions sold to date, and demanding that they stop infringing the copyright. If they do not pay you, sue them. You (or the rights holder) might also wish to register the works with the U.S. Copyright Office if this was not already done.

It depends on who owns the rights to the images. Unless you own the rights, you have no recourse. IF you own the rights, then as Mr. Stone says, you can sue for copyright infringement and recover all income they have made from it.