Shocking service from First Car Rentals

Shocking service received from First Car Rentals Durban! Cars they claim to have in their categories are not available after booking. On returning the vehicle to the King Shaka airport we filled up at the King Shaka garage 500 m from their drop off point only to be charged a fee of R 75 to refill the car- for 1.8 litres ( R 25) .It was full to the brim after filling. We queried this but the staff are very rude over the phone as well as by e-mail and refuse to assist. This is the way they treat international clients as well as local clients and I find it disgraceful. Worst service ever received from a car rental agency, definitely will never recommend them to anyone.