Hi @Dawn9,
That's very unfortunate the Airbnb Support Center couldn't help you even though you spoke to 4 reps, but yay, you have the Community Center 😄
1) What you've explained is strange and ideally shouldn't have happened, since you don't have Instant Booking On. And yes, bookings/blockings should only take place on your approval.
2) I think the explanation you received about a guest pending verification etc is false and probably there is a bug that has blocked the dates.
3) W.r.t your current inquiry, please explain the guest that there's some bug due to which the calendar has frozen and that you'll get in touch with them within 24 hours to update them. Hopefully in 24 hours, your dates should be realesed.
Try using twitter to contact Airbnb, they are fast to respond and hopeful this time you should receive some sensible and positive reply.
Good luck 🙂
Jeet