Petrol not put in, charged and then called a poor

This morning I stopped at the garage I stop at once a week where I put R100 petrol in<br> I walked into the shop and when I got back to my car I paid with my work card.<br> I turned my car on and saw no petrol had been put in.<br> I drive a BMW and it shows exactly how much I've put in and the reading goes back to zero so I can see exactly what was put into my car<br> I called the manager and was then attacked by the female manager who called me a poor white and started climbing through my window<br> I am a female alone at a garage at 6h30am<br> I would really like an explanation for this immediately