Booking.com Refund Denied After Qatar Airways Flight Cancellation

I booked a round-trip ticket through Booking.com from Milan to Visakhapatnam and back, with customer reference number 40-881574439. My outbound Qatar Airways flight from Milan to Doha on 23 March was cancelled by the airline, and because of this I was unable to travel to my home country as planned and could not start my trip at all. Since the outbound flight was cancelled and I could not travel, I called Booking.com on 17 March and requested that my return journey be cancelled and that I be refunded the full amount I paid, which is 765 euros. My return journey is scheduled to start on 26 April, from Visakhapatnam to Hyderabad with Indigo Airways and then from Hyderabad to Milan with Gulf Air. However, because the original outbound flight was cancelled, I am not able to use these return flights and the entire round trip has become useless for me. Despite my clear request for a full refund due to the airline’s cancellation of the outbound flight and the fact that I cannot use any part of this trip, I have not received any proper response or solution from Booking.com. I also have not received any email or written message about my refund request from either Booking.com or the airlines. Because the initial flight was cancelled by the airline and I was unable to start my journey or use the ticket, I am requesting a full refund of 765 euros for my entire unused round-trip booking to be processed as soon as possible.