I would say contact those basterds tell them that they at least should have said those works came from you. Then i would make a copyright text and put it at the top left of all you pictures......Then they can't steal it like that. And if they don't listen and you can prove that those pics are your own.....i would like tell it everybody and maybe go to the police or something alike....
Hope that it will become right as it should be
Good luck mate