Rude manager

My cousin fueled up at 17.45 at prospecton caltex pump number 4 served by a black female were I asked her to fill 200 rand Lrp instead she filled 500 rand. Then she came up to him an advised him she filled 500 rands an said she made a mistake.There was a Indian manager on duty which didnt sort out the problem with the attendant but demanded to leave something to that value which he took my watch I PREVIOUSLY ran a service station but if an a attendant make a mistake is liable to pay. I want to know what will be done going forward as this is not called for.