I had a similar experience but in St Petersburg, Russia.
On returning the car, the agent came straight out and pointed to a tiny chip on the windscreen. I hadn't noticed it while driving as it was minute, about 2 inches from the roofline and obscured by the mirror.
By the way she went straight to the car and pointed at it, it was an obvious scam.
She told me I would have to pay full cost for a replacement. So I took out a camera tripod from a case and smashed it across the screen.
If I was going to pay for something I was going to enjoy it
The police came over but after our translator explained the situation they laughed and walked off.