First Car Rental sucks!!!

Initially received brilliant service upon taking the car from the ORT branch. The agent was excellent, followed by an upgrade and a quick turnaround. However, upon returning the vehicle, they moved from 5 stars to Disaster. They charged me for 3 litres of fuel and an Admin fee for this. In total, it was not much but I am aggrieved because I proved that I filled the vehicle at the Engen at ORT. It's about the principle and integrity. Based on this experience, I had to downgrade my rating of this organization (i.e. from 5 to 2 stars). I raised my concerns with them but it fell on deaf ears. Guess what, I won't be using First Car Rental again (unless the process a refund and send an apology for treating me with disrespect). :(