Engen garage

I went to Engen garage today which is in Rhodesfield. My fuel was 99km by the time I got into the garage. So I asked them for an unleaded petrol (95) worth R100. To my surprise my petrol tank did not even go up with 1km it remained the same. I spoke to the manager and she said the engine is gonna pick up as soon as I start driving. So I started driving back home and nothing happened