Defective Olifant trailer rentals

I have rented a car-trailer and after loading the vehicle and filling my own with diesel some one pointed out to me that the trailer brakes were defective. Photos are available. The braking system was tied with wire to the hand brake and not at all connected to the auto stop system. It was 5 o' clock when this was discovered. I took the trailer back the next morning. The owner does not want to give back the rental for the day because the trailer was out for longer than 5 hours.