Hello,
You will first want to disconnect from the Internet, whether that may be by unplugging an Ethernet cable or turning on Airplane Mode. This way, the hackers can't send any data to their computers/servers.
Then, run a full malware scan on Windows Defender and then see if it finds any viruses, and quarantine/remove them as needed.
If you still need the live support, you can go to https://support.microsoft.com/contactus and then sign in to your Microsoft account (if it's hacked, you can create a different one for the purposes of support. Then, select "Contact support" at the top of the website and then select "Windows" in the first dropdown and then "Security and Privacy" in the second.
You should now see an option to chat with an agent in your web browser; select that, and then you should be connected with a Microsoft agent.
I hope this information helps.