TOTAL RIP-OFF

On the 06-12-2021 my nephew went to Protea Glen mall to buy some stuff and the car had one white bar but going on reserve. He then went to Engen filling station in Protea Glen ext 13 and poured R200 petrol. When he came back the petrol was still on reserve, there was no white bar. I was shocked and fuming because I couldn't understand how come petrol was still on reserve. The following day I poured R300 petrol at a different filling station and there was white bars to show that petrol was poured. I want engen to explain to me how is it possible for one to pour petrol and still have no petrol. Even the distance from the filling station to home won't eat up the almost 10 litres that is claimed to be poured. I NEED ANSWERS.