I think there's nothing the OP can do up to this point.
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I so much detest this exchange, their customer service is nothing to write home about, I misplaced my cellphone around May this year and I discovered that my account details with Hibtc has been compromised, they didn't respond on time, I just had to forget about having an account with them,
Dear user, what was your support ticket number? We'll gladly look into that.
We take the security of our customers very seriously and provide a number of security tools to help you protect your account, such as 2FA, email confirmation, etc. Here's an article to help you minimize such risks in the future:
https://support.hitbtc.com/hc/en-us/articles/115005044629-How-to-protect-your-account-from-intrudersAnyways, maybe you can try and see how your account got exploited and learn from it.