I don't think the accounts recovery team will accept a signature from the stated address because it was posted right before the account was hacked again.
Actually, checking the time stamps, it was staked right after the account was recovered
Password reset: 12/6/2019 3:14:28 PM password reset via email
First "account recovered post": December 06, 2019, 17:17:44
Address staked: December 06, 2019, 17:34:05
So unless the hacker was able to access the account in those 2 hours (which I must admit, seems feasible judging by the record), the address should be good. The next hack claim was made almost 2 months later.
I sent them signed message from the staked address you quoted but they're not ready to accept it.
They think that my account is still compromised and they are not sure whether it would be accessed by me or someone else once they unblock it?
What other options can you guys think of to convince them that it's actually me only who will access the account once it's unblocked?