gas gauge fraud

Rented a cube van from Carter Rentals on Barton St Hamilton.
Checked and signed off on full gas gauge. Returned the truck after a round trip of 39km with a full gas gauge.
The manager then takes the van to the back and 'tops the tank up' and says I owe for another 12L of gas. What is worse is that they charge $2.26 per L for diesel! I say that the tank is full by the gauge and the manager just dismisses my comment with a 'this is the way it is'. I report to the company that undertaking a policy where the customer signs off on the gauge pre-rental and different method is used to assess 'fullness' after the rental is deceitful. How does the customer know that the tank is 'full' when they are renting? Clearly 12L could be added even to a full tank (as assessed by gauge). Though the company did admit that the 3.3km/L fuel economy I got with this truck was poor, they dismissed my concerns.

BE AWARE, you too could be an unsuspecting victim of this deceitful policy! Make sure fuel is pouring out of the tank or they will not consider it full. I would suggest you have them 'check fullness' pre-rental on their gas pump right in front of you.