I've secured the account for you. I can see that you've submitted a recovery for it and this should be granted in a short while by our support mods.
Unfortunately, it looks as though the email that you had registered on the account is not as secure as you had hoped. The hijacker used this email to recover your account (rather than going through the manual recovery system). I recommend taking some time to secure your email and/or create a new one that is not affiliated with anything other than your OSRS account. I'd also recommend checking the email on a website such as haveibeenpwned, to try and identify how it was leaked.
I've begun the process of tracking any wealth that was taken from the account. I'll ban any hijacking/real world trading accounts that have received or sold the wealth. I have also made the anti-hijacking team aware of your account so they can fully investigate the person responsible for the hijacking.