We went out searching and found Bess stuck up on some high scaffolding. We really did appreciate the fact that there were organisations like Pet911 though as it gave us a little clink of light during an otherwise bleak day.
Took till 2 am this morning till things went quite enough for me to hear her, and luckily she call back when I call her, but found scared but safe, and now after a sleep and food seems ok.