You university probably has a free legal clinic for students. I would suggest you check them out and get advice on the situation (as in if you can somehow get the money back by suing or involving police). I know you probably don't want to legally go after your parents, but it's good to know all of your options. And you can always try threatening them with suing/police involvement without actually following through. Just the threat might get them to take it seriously that they stole from you.