What he saidAre you maybe refering to this: World of Warcraft Offers Free faction changes for select realms | Hallowed Gaming ?
The free faction change never went live on F2P accounts. It was an automated system where they flagged every 20+ character on one realm.
As for race changing, or any paid service, you can upgrade with a credit card that has insufficient funds, and that temporarily removes all restrictions. Then, once it's clear the funds haven't cleared, you revert back to F2P... Sometimes. It's also possible that your account will simply be an unpaid full account.
That's only a small part of why you'd want to do it. The main reason would be to get all P2P chants and profs as well as some mog items. You could also raise the gold cap and join a guild. I wouldn't suggest doing it on an account you've spent a lot of time on, but on a new account, it's well worth it. The risk is minimal, the reward substantial.
Is that the only method?Yes, the method is still working... but you are doing it at your own risk.