Infact, after it was hacked 2nd time, I even changed my e-mail address. Not sure how did hacker get to know about my new e-mail id to hack it for the 3rd time.
You don't have any clue about what you are doing online. That's how he got access to your new email address.
Obviously, you didn't learn anything about getting compromised 2 times already.
Moreover, do you think hacker would have hacked this new account as well and would be following up to get old account back?
If you would have done everything (somewhat) correctly, this wouldn't happen.
But you lost your account 3 times already .. so who knows..