At this point, I don't think there is anything you can do about it than to wait for their response to the ticket raised. On whether its legal to ask for your details, its unfortunate that you have to comply with it as your refusal would give them an excuse to shift away from their own responsibility for being held accountable. While there is nothing to recommend because there is nobody authority to report to, the amount lost is not enough to gather the number of audience to force an action on their part, you can only take this as a lesson.

One major lesson is never to keep your funds on exchange site. You are better at keeping it for yourself. I am also skeptical about the amount of time that coin would have been there because for it to lose value in such high percentage, you must have been waiting a long time for it to recover having bought it during the ICO period which might makes it an inside job for the perpetrator to have thought there is no one interested in the coin again. Another lesson is for you to be more vigilant in your investment decisions, if this coin had been a valuable one, you would probably would have sold it, or the developer have an offline wallet for you to keep it. #my opinion.