Someone hijacked an older google account of mine, the phone number used had since run out and been sold to another user.
Google asked me to either have access to the phone number, and the old password, or to know the security question, have access to the backup email, and know the exact day the account was created on.
Google was not willing to provide any help, not even via the Nexus phone support, and even after a friend who worked at Google submitted an internal recovery form.
After I contacted the new owner of the phone number, and coordinated with him a way for me to authorize via SMS, backup email, old password, security question, and account creation date at the same time, I got back into the account.
In the account I found an email from Google's account recovery support thanking me for contacting them, apparently they had contacted the hijacker after I asked for help, not me.
After changing all data, I went through the login history.
The account was set to German, always used from Germany. Someone tried logging in via several different VPNs, and was blocked a few times, but allowed the last time from Russia.
I had learnt the account was compromised originally because Google sent me an email that an attacker from Russia had logged into the account and changed the password.
So, to recap:
Google realizes that an attacker connects and hijacks an account, emails me, but doesn't prevent it.
Google allows that person to change the password, and tells me that an attacker changed the password, but provides no way to restore it, and doesn't block it.
You can't restore with backup email, security question and old password.
Once Google's internal account recovery team was contacted, they talked with the attacker, not with me, despite being explicitly told I had no control over the account.
A random person was more helpful with restoring the account than Google itself.
Do NOT ever rely on Google, and write down your accountcreation date right now (on desktop, in gmail, settings, pop3 and imap, "pop3 active since" tells you the account creation date)