the transaction time & time of FALSE card block request will go against you.
The website bookings.com will provide evidence with ip address & timing to your bank and claim their cancellation charges.
not many of us read the terms & conditions while using internet services to order/ book / service online. every online service provider have a cancellation / refund policy which we all ignore in excitement to enjoy ease from our couch.
be nice & be wise with yourself & your banking history. any false submission declining a payment to vendor go under disputed case & you get flagged for life as trouble maker.
Your choice !