Overcharge unresolved

A couple of days ago my brother was sent to BP garage in Madadeni to fill in my car with petrol for R200 and I later figured he was overcharged because the car is a Fuel master and he still used my card to pay. When I went back the guy who assissted said jah he realized after he was gone and gave me the fuel master slip. I asked for my R200 back they said I must come later because their transactions do not reflect immediately. I asked to come back on the following day cause my brother was getting married on the day. They said its fine. When I went back the manager or supervisor was not there and I spent almost an hour there. I asked for numbers to call the owner or manager cause I was going back to a different province she said its fine. When I asked her to confirm with her employees they said she said something else and just like that I lost my R200.