Unfortonately, that account does not take down the post, nor do they stop reposting your art. You've already made your decision to ignore them and try to move on. You're still upset, however, so you decide to speak to a friend.
After confiding in your friend about what's been happening, they suggest adding watermarks to your posts so no one can take your artwork again, but you aren't sure if you want to add them. On one hand, they'll stop the reposting problem. On the other hand, however, they can take away from the overall artwork.