Fox Rent A Car

Upon renting the car (1/22-1/25) with prepaid booking (FFX0192CAF, LAS-1122504), and stating multiple times to the employee (Tomeka) that I do not wish to purchase any additional insurance because I do have one in my hand, I was told I'm signing a "liability waiver" which in reality was liability insurance. The employee would not even look at my insurance. She assured me all I'm signing is the security deposit, liability insurance waiver and release of the car. Apparently "RS" is not release but roadside assistance, that I also was not informed I'm signing up for and the screen made those agreements illegible. I was then rushed to the parking lot without having the chance to look at the rental agreement given to me. Moreover, just before returning the car I filled the tank with gas. I have proof; a gas charge on my credit card statement with full address located within 2 miles of the rental place (Chevron 0206881, 2237 W Charleston Blvd, Las Vegas). However FOX decided to charge me 130 USD for fuel, claiming that I left the tank empty. The only proof from FOX in this regard is their assessment, which is not a proof per se. How can one trust a company which behaves like that? If the tank was empty, then why were I buying fuel right before dropping off the car and flying out? Maybe I was refueling the airplane for $28?
I have a witness that was with me throughout the whole trip.