@Jean256 what an ordeal!
The blocking of the date on your calendar is normally part of the cancellation penalty.
Since you were allowed to cancel *without* penalty, the blocking of the calendar did not happen.
If you are able to cancel again without penalty, you should immediately block that date on your calendar.
To speak to an AirBnB person, go to your Host Dashboard and choose the "Help" page.
At the bottom of the "Help" page there is a "Contact us" button. Press this.
On the next page you should have the choice to "Message us" or "Call us".
Choose "Call us" and follow the instructions. You soon should be talking to a real person.