My version:
I rented a car at YEG. Gassed it up just outside the airport and returned it. The attendent acknowledges the gas receipt and doesn't charge me the fuel charge. I get a revised receipt later in the day with the fuel charge added.
Call the customer line and complain about the fuel charge and the fact it is added later. I had to fax in the gas receipt to get it removed.
Guess I'll be renting elsewhere next time in YEG.