AVIS GERMANY WAS SCAMMED TO PAY FOR DAMAGE I DID NOT CAUSE DUSSELDORF GERMANY

I travel alot for business, and always rent cars with no problems. The last time I booked and paid in advance for a car from Avis in dusseldorf airport in Germany. When I arrived, the car I booked was not available, infact the only cars available were manual and I had booked an automatic. I was told afet 20 mins of waiting that there was a Mercedes E class when I had ordered a C class. I was given the E class for no extra charge (which I found to be a very good thing). I had the car for three days I parked in two places only during those days, both of which were closed areas. When I returned the car the woman at the airport drop off pointed out a scratch at the bottom part of the front bumper, a scratch so small (about 4 cm) and a very surface scratch, I was shocked that she even saw it cause the car was dirty from the rain and snow, it was like she knew in advance about that little scratch. I never checked the car when I took it, and even if i did, there was no way I would have seen that scratch. However, that was not the problem, that I can say was my mistake for not looking at the car with a microscope. However, the woman at the drop off decided that that little scrach (which I think can be buffed in 5 mins) would be estimated at 520 Euros. I was charged the 520 Euros for that tiny scratch that would in reality cost 50 Euros to Buff, and which I am convinced was not caused by me.
I was told by Avis that "it was established that the car had been damaged during the period" of my rental. This comming from a company that lacks organisation, since
-I arrived and did not find the car I had booked,
-the lady at the counter told me that I did not pay for the car in advance, when i gave her a copy of the payment she appologized and said she was wrong.
- the person who took the car back at the drop off just gave any number out of his head (520 euros) and that number for some reason became the amount needed to fix the tiny sctratch.

Adam
windsor, Ontario
Canada