I lost 50k on this site, when I pay with small amount, everything is fine, after I transfer more to the site, all sudden they block the account (no email, no reason, uncontactable), my god, it's scam.
try verify your account and then withdraw all your coins and never use that exchange again.
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can be an internal work, probably some hitbtc staff may have taken your coins and made trade with your coins, if they did not respond you should proceed with legal actions, you can hire a good lawyer, report your case to the police and let apolicia and the courts find these hitbtc scammers.
Where is hitbtc office and the OP ? does his lawyer go to another country and fight with those scammers?