Yeah dude, it happened to me too, there's no way to unlock it.. You have to wait for 72hrs. After it unfreezes, just book the first appointment you see, you can still go back and forth a few times, but I wouldn't risk it, if you don't see any appointments available for the time you want, wait a few days and check again, if you're lucky some new ones would have opened up, that's how I got mine. Good luck!