Unfair customer treatment

I bought a cam shaft from goldwagen in bloemfontein last month, the mechanic assembled the engine and the diagnostic machine still read the same fault, the brand new cam was taken to engineering and the result came as factory fault, I returned the defective product back to goldwagen and was told to wait for 7 to 14 days as I cannot be refunded or part be exchanged, I feel this is really unfair because even if they order something for you it does not take that long, Daniel Menyatso ***