Let us know whether you can see the Calendar tab at the bottom of your app, like this:
When you click the Calendar tab, you have to click on your listing to open its calendar. You will then be able to select nights to edit. Does this work?
Shelley and Joelle have shared some suggestions with you, did you get a chance to try either of them? It would be great to hear from you, and know if you've managed to access your calendar again in the end. 🙂