While QR 600 is no doubt on the very high side for just checking the brakes, there are couple of things you need to keep in mind. As Antonio RN has rightly pointed out in his comment, you own a premium car. Also that you had the service done at the agents as possibly (repeat possibly) you have little confidence on workshops in the city. Costs are always higher at the agents compared to that in the market. But for a premium car owner, it hardly means anything. What is QR 600 compared to the safety of your life? Suggest, you relax and drive safely with peace in your mind leaving this incident behind.