Billed for fuel when car returned completely full

I hired a car from First Car Rental, fuelled the car on my way to the airport and like many others reporting here was billed for fuel (and plenty of it). Now I filled it to the brim and asked the attendant to squeeze in little more. <br> How on earth they say they put in 17lt (more than 1/3) of a tank is beyond me. Thats certainly no air lock. <br> <br> I raised this with First who quite honestly didnt care. My point was not to get my money back (I cant prove I filled it) but rather to serve them in demonstrating that there must be some serious admin issues or ***** going on. They didnt seem bothered in the least bit and their online complaints reporting process denied one the opportunity to meaningfully engage with them. No company is perfect, I don expect perfection but their total disregard for my attempts to serve them in this manner is highly offensive.<br> <br> If I cant serve them, I have to simply serve others by advising them to steer well clear.