If there is nothing fishy about the account why not resolve your issue with an admin or support staff from BC.Game especially that you are the only person that can answer questions about this account when unlock process is being done. Otherwise this is not a good deal especially that you can easily recover it back!
Probably, that the account is not recoverable already, just like typical gambling issue where users are banned, account lock due coz of cheating, breaking the TOS, etc.
This is more like selling a locked Paypal account, or a hacked account that was locked due to suspicious activities and selling it is the only option for them to gain profit, or...