Scratched car

I went to Engine D & J Motors on cnr wf Nkomo street, pretoria west, to fill up petrol, the attendant voluntarily decided to wash my windscreen and in the process took the same brush and srubbed part of the boot (body of the car) this resulted in scratching my car. I contacted the store manager and all he could when i met him today is that he is sorry telling me that we have a difference of opinion that the material use cannot scratch a car. I refused the offer to polish the car because it will actually do more harm. He even told me another option i have is to atop getying feul from their garage since i did not get good service but that is not what he really wants