Refueling **** I want my money back

I have been ****** by this company,I return their car with full tank but a day after I receive an invoice stating they have done a refueling on that car how is that possible, R450 was debited on my credit card less than a month of driving that car R850 was poured while the fuel gauge was still on half tank nd again I'm told refueling was made, it's either someone is *****ing out fuel when rentals are being returned or the company is **** robbing out people their money. I won't take this lightly someone should explain to me how is that possible. Stop *****ing from your clients