I have also moved all my business from Hertz to Avis. However Avis has tried the same tricks when returning to LHR. Three times in a row, when I have returned the car "the printer is not working", and each time I have been charged for gas when I returned the tank full. Fortunately Amex have been able to get Avis' attention and have the charge reversed, but it's exhausting to have to watch for fraud at every interaction with large international companies.

There must be some corporate training encouraging the creation of these "mistakes" which 100% of the time are in the company's favor.