Disquieting service at Caltex garage Beacon Bay

Few minutes ago, I drove to Caltex garage at Beacon Bay East London to fill up the car. I was quickly assisted and I told the petrol attendant that I need the car tank to be filled up until it's full. Whilst I left him busy, i went inside to buy some food for supper. I came back and he said I needed to pay R717. Upon driving home, I noticed the the car fuel gauge was no where close to being full. I drove back and inquired information on what could have happened. The supervisor was not helpful at all. I even told them the car's fuel tank is 45L and yet the slip showed 47.77L. They kept on suggesting that It could be the gauge that has the problem but i have used the same garage on numerous occasions before and never experienced the same problem. The supervisor called the Owner who was also useless. He kept on saying I should come back early tomorrow morning. That is the same Owner according to his staff, who stays very close to the garage. It felt like they never wanted to assist nor cared about how I felt. Pathetic service!!!