Booking.com App Unauthorized Charges During Booking

On September 30, 2025, while trying to book a hotel for my Frankfurt trip through the Booking.com app, a warning appeared on the screen saying, “Payment for your previous reservation was not received.” The page displayed Booking.com logos, my reservation number, and personal details. It also showed a message stating, “Payment could not be processed with your AMEX card, please enter a different card.” Since I had encountered a similar issue before, I believed the page was legitimate and entered my Mastercard details (last four digits: 0013). However, the page froze, and immediately afterward, four separate transactions of €272 each were charged to my card. I canceled my card right away and contacted my bank to dispute the charges, but the payments were still processed the next day. When I contacted Booking.com, they claimed the issue was not related to them and advised me to follow up with my bank. However, the entire incident occurred within the Booking.com app itself. I believe this type of security breach could affect not only me but also other users. I request that Booking.com thoroughly investigate this issue, inform users about potential risks, and resolve my financial loss. Reservation Number: 6618265031 / PIN: 0433. Incident Date: 30.09.2025. Amount Charged: 4 × €272. Related Hotel: Flam, Norway. My expectation is for a detailed investigation into the unauthorized transactions, reimbursement for my loss, and better user security communication.