Booking.com Free Airport Taxi Missing for Hotel Kö59 Düsseldorf

I made a reservation via Booking.com for Hotel Kö59 Düsseldorf, including a clearly stated promotional “Free Airport Taxi” for my trip from Istanbul Sabiha Gökçen Airport to Düsseldorf Airport and onward to the hotel. My confirmation code is 5648109811, and I paid over €887.42 for this booking. Although the reservation explicitly included the Free Airport Taxi benefit, the link that should allow me to generate or book this taxi never appeared properly in my Booking.com profile and could not be used. I checked my account repeatedly, but the taxi booking option was simply not available, even though the promotion was shown as part of my reservation. As I am supposed to use this service on 1 September 2026 and the free taxi was one of the reasons I chose this booking, I am asking you to either manually issue and confirm the Free Airport Taxi from Düsseldorf Airport to Hotel Kö59 Düsseldorf, or alternatively to authorize and guarantee a full refund for the cost of a local taxi for the same route. I kindly request that this issue be resolved before my travel date and that you confirm in writing which of these options you will provide.