Just for better explanation as well, and because some people asked for it, here is the total timeline of what's happened which is from an email that I sent to Dash.org to explain the situation to them:
The process in total is:
1. I first signed up at Bithumb, Sun, May 7, 2017 at 2:24 PM (Australian time)/ Sun, May 7, 2017 at 4:24 AM UTC
2. When you sign up to Bithumb you cannot withdraw without sending Passport ID. I did this Mon, May 8, 2017 at 2:01 AM UTC
3. I had already transferred BTC to Bithumb and sold it, then purchased LTC. My first withdrawal from Bithumb was Mon, May 8, 2017 at 11:03 AM UTC after being verified
4. I made 3 more sell transactions on the 9th May after first transferring BTC to Bithumb, and then withdrawing the ETH/DASH/LTC to other exchanges.
5. The 3rd transaction of these was buying DASH at Bithumb and then transferring it to Livecoin. This was successful. The Dash TXID for this was 96381636344f2f379d85ba85433b7491f8ccf5eb1b331c2087711476bbe53cd8 and the amount of Dash I sold at Livecoin was 3.30611835
6. This transaction traded 3.30611835 DASH for 0.19836714 BTC. I then withdrew this back to Bithumb (
https://blockchain.info/tx-index/54e9cc37eeef47a1d71569530effd09fc449ac11cf8bb2207c206a46ecf85537)
7. With this BTC arriving at Bithumb, I sold it for Korean Won on the site and then purchased 3.52272214 DASH at Sun, May 9, 2017 at 0:57 AM UTC (
https://explorer.dash.org/address/Xf3osQVZsD3GBYYgvp5gd5pQcjSWj1vL1n)
8. I tried to withdraw this DASH back to Livecoin, and this was where I first realised something was up. I was blocked from withdrawing (which I had already done 4 or 5 times over the last 2 days with no problem) and when I looked at my profile to find out why, I saw that my verification from step 2 had been changed back from Level 2 (you can withdraw) to level 1 (you are new to Bithumb, not verified and cannot withdraw).
9. After trying a number of times to re-verify by clicking on the non-working level 2 button, I decided that logging out and then back in might resolve the issue somehow.
10. I logged out, but when I tried to log back in I got a message in Korean even though I had entered the same details I had always used.
11. I translated the Korean message, which said that my email was not on their system. I tried logging in many times, checked emails (verification email and 20 others from them) to make sure I wasn't going insane, and trying unsuccessfully to click "forgot password" to at least get some way to solve the situation. Even the password reset process returned that my email was not in their system.
12. I contacted them first about this at Tue, May 9, 2017 at 1:09 AM UTC (12 minutes after the 3.52272214 DASH was purchased and placed in wallet Xf3osQVZsD3GBYYgvp5gd5pQcjSWj1vL1n)
13. I spend the next days contacting them (over 80 emails in total, mostly mine). After 3 days I searched through the Dash blockchain to get the exact details of the purchase and the wallet that held the missing Dash. I sent this wallet address to them after them telling me that by doing this they would help me to retrieve it. After 3 days of sitting dormant, 11 hours after I gave them the Dash address it was emptied. I haven't received an email from them since, and it was 7 days ago.