Will NOT swipe credit card for R20 petrol

I was at the Brooklyn, Cape Town branch last Thursday evening and i did not have cash with me so i asked the attendant to fill me up with R20 and i said i will pay with card. He then started shaking his head and i asked what is wrong he said if i fill with R40 and over then i can swipe. My car has a leak in close to the tank and this is one of the reasons why i only fill up with less petrol.<br> There is an FNB ATM at the branch but i did not feel safe using it because there where 2 men standing close by. If you accept credit card payments then you should accept for any value. i drove off and went to Caltex who accepted my card.