Cannot Cancel My Booking.com Car Rental Despite Free Cancellation

I am writing to request the cancellation of my car rental reservation made through Booking.com for a Compact Class Avis vehicle, scheduled for pickup in Mytilene on 2 June 2026. My reservation number is 738123871. At the time of booking, the conditions stated that the reservation could be cancelled free of charge until 30 June 2026, and I am trying to use this right within the stated period. Beginning on 1 June 2026, I repeatedly attempted to cancel my reservation through both the Booking.com website and the mobile application, using different devices and browsers. However, every attempt failed due to a persistent technical error in your system, and the cancellation process could not be completed. The rental is payable at the counter, with a total amount of ₺4,546.17. Because of this technical malfunction, I am now at risk of being charged for a reservation that I have been actively trying to cancel in line with your cancellation policy. This problem is entirely beyond my control, and I do not accept being held financially responsible for a system failure that has prevented me from exercising my contractual right to cancel. I request that this reservation be fully cancelled without any charges and that my cancellation be processed and confirmed accordingly.