Booking.com Refund Request For Filthy Property With Deceiving Pictures/description

We reserved La Maison Pondicherry through Booking.com, where it was advertised as "one of Pondy’s most well-known and popular heritage guesthouses with a long and eventful history! The Guesthouse has eleven magnificent double deluxe rooms, newly renovated... Everything is new and clean!" We stayed there from December 28th to today, paying 22,487 INR (€252) for a "Deluxe Double Room." The reality was far from deluxe, nothing was new or clean. The room was filthy, crawling with bugs, had stained walls and curtains, the windows were covered in newspaper, and we had to make the bed ourselves. Despite leaving the key for cleaning, nothing was done. Laundry was left in the rain, and breakfast fruit was swarmed with flies. The property has no 24-hour reception and no restaurant. When we complained, the staff blamed some recent flooding but offered no warning, price adjustment, or resolution. The hotel ignored both our and Booking.com's requests for a partial refund. Booking states that they are not responsible for the deceiving description and pictures and they do not offer any refund. We seek a resolution leading to a partial refund that would be only fair.