Not the right colour for good service

I use this garage regularly, I full up many vehicles there thus whenever I go there I would be ignored and other people would get served first (white people) since the attends are black I don't see why I'm being ignored, maybe because of the tips issue, I refuel the vehicles of the company so thus I don't have money to tip them. I always leave that petrol station with a bitter taste in my mouth, I complained before to management about it but nothing was done and only got sarcasm, guess I'm the wrong colour(coloured). Well today as I was refueling, as I was about to pump the vehicle's tyres up, I punched in the amount of air that was to be inserted, suddenly the attendant took the pump and started pumping up someone elses tyres, ignoring me in front of him and didn't even bat an eyelid....... I guess I have to be white to get the best service, I left there feeling like a fool but its no use complaining to them because there the staff is always right .