Google Goldcar in Spain and Portugal. I think they might have been part of the Sixt, but far from certain. Anyway, this scam of paint chips and damage is legendary. Reports of staff getting under the car with flashlights or finding dents around the inside rim of the trunk, etc. And phenomenal refueling charges.

But the damage - and payment - via the tiniest chip or scratch seems to be quite common especially if you go off-reservation, so to speak and chose the cheapest company (usually a local) rather the recognized leaders in the field.

The search will lead to many, many threads and articles and if, like me, you find these tales both hugely fascinating and outrageous, you might be in for a long night.