I suspect they're a ****-Business

I enquired about a book that my daughter needed for an exam, confirming that it was available AND that it would be delivered in time for it to make sense for us to order it. I also confirmed that if I chose the 'rent a book' option that she'd be able to return it and I would receive my 50% 'fully refundable' deposit back. Both of which was confirmed. Delivery was due on Friday 13th November. My daughter's exam is tomorrow. And still no book. Nor a response to either our calls nor emails. Book a book have just disappeared - with my money. What to do???