I had something similar to this happen to me with Hertz UK.
I rented a car and drove it from London Gatwick to London Heathrow.
Upon return I was charged 75 Pounds for damages to the bumper that I did not do. I was stupid...I had not inspected the car, but honestly these marks were so small that I would not probably said anything anyway.
Now they want me to fill out extra forms, etc.....