2020 BMW X6 Seat Belts

On December 28, 2023, the "Fasten Seat Belt" sign (rear passenger side seat) and sensor in my BMW x6 starting buzzing even though no one is seating on that seat. I subsequently brought my car to the dealership and the service consultant did an ocular inspection of my seat belt and looked inside the buckle with a flashlight because the seat belt will not lock in place. I was subsequently told that the metal that is supposed to hold the seat belt in the buckle is missing or stuck. Because at that time my car has 59,000 miles, I was told that the warranty has now expired (50,000) and that I have to pay for the diagnoses and fixing of the car seat. Now, the "Fasten Seat belt: sensor for the rear middle seat is also lighted and making the "buzzing sound" even though no one is seating in the middle seat. I believe that my seat belts have become defective and given that I purchased my car around May 10, 2020 - I should not have to pay for fixing seat belt problems for a new car given the safety need for these belts. I would like NTSB to compel BMW to fix my seatbelts.