Scam Warning
Almost all are hacked accounts, hence why you're told to not change the password to not alert the real account owner. As so many people use said accounts, it doesn't take long for someone to change the email and password to their own and lock everyone else out, then the real owner contacts support and everybody loses out - but the scammers.
This is assuming the VPN company doesn't detect abuse first as so many people are using one account and outright ban it.
There's many examples on the Windscribe subreddit of accounts being hacked...
Example 1:
"18 minutes after you submitted your ticket, the person who hacked your account also submitted a ticket asking to change the username. Good thing you provided the license code as that's the only thing that proves you're the account owner."
Example 2:
"We disabled your account because your credentials were leaked online and your account was compromised. We wanted to prevent any further changes to the account as well as prevent abuse of our service so we temporarily banned it until you can set a new password."