selling damaged goods

I am workshop owner buy lot from goldwagen specially break pads I bought front and rear break pads from goldwagen for bmw x5 front break pads make noise like pirate parts I took my disk out to skim them I taught because of lining its making noise but it wasn't actually because of plates it was break pads making noise then I went to the branch told them the whole story they told me that I have to buy the break pads again and they will send break pads to head office and If they approve they will refund me and if not I have to keep 2 break pads I told him look I don't mind you send for testing but I want this to be return and exchange with another break pads and what if other break pads make noise must I keep on buying the break pads very disappointed buy lot from the just for small thing loose the regular business that is call very bad business, very very upset.