I have some advice!! I recently dealt with an art theft on Google + and google took down the pages (i'm p. sure you can ask for a ban as well if you explain)
so basically you file a DCMA w google for copyright violation of your art
here's the form!They need you to attatch proof and what I did was i pointed out my visible watermark, then linked my Toyhou.se account and Deviantart account (linked respectively on their pages AND in watermarks bc my watermark says DA/TH/Gaia) THEN i linked the deviation showing my ownership (basically me buying) but in your case i'd link to the deviation yourself and attatch another screenshot with the posting date and/or a screenshot of a WIP or the files itself.
They might email you back and say your request was denied (happened to me), just reply to the email and explain (in angry terms/indignant for best results) that it's YOUR art and you hold copyright
95% success rate