Booking.com Rental Cost Issue - Unfair Charge Despite Insurance

Between May 25–27, I rented a car in Sarajevo via Booking.com. When picking up the vehicle, I initially opted for the package without insurance and a €1600 deposit. However, due to insufficient credit card limit, I was told I must instead purchase an insurance package for €120 and leave a €200 deposit. I agreed and proceeded. At the end of our trip, we returned the car exactly on time. The rental staff pointed out a minor scratch/mark on the rear door. We had not noticed this before and only saw it for the first time during the return. It was not a dent or real damage—just a light surface mark that could possibly be wiped clean. Despite this, they demanded €654 (1280 KM) from me. I told them we had already purchased insurance and asked for the damage to be handled through that. But they refused, saying that because I didn’t call the police or file a report at the time of the damage, the insurance was void. I explained that we didn’t even know about this tiny mark—it’s barely visible and we honestly didn’t notice it. We were also in a rush for our flight, so we had no time to dispute the charge on the spot and were forced to pay €654. In summary: I paid €120 for insurance which they rendered completely useless. I paid €654 for a minor, possibly pre-existing or barely visible mark. I was given no clear explanation of how this fee was calculated—are they car repair experts? I feel deceived. I could’ve booked through a random site, but I trusted Booking.com for its supposed protection and customer support. I am requesting a full refund of the €654, or at the very least a formal investigation. If I purchased insurance, the damage should be covered through that. What’s the point of offering extra insurance if you won’t honor it? Please help resolve this issue. I trusted your platform and feel completely let down. Sincerely, Ayhan S***