Sorry to hear that. I had ordered ACS splitter in Satin black from Gary, and the finish was perfect.
I later ordered CDC side skirts in the same satin black, they arrived in a matte finish. Unfortunately, I hadn't checked the skirts in the light, so I didn't realize until the body shop had already put them on the car.
I asked Gary what I could do, he basically suggested using a polish on the skirts to make them more shiny. Since it was partially my fault for not checking, I didn't pursue this any further, but as people on the forum will tell you, getting painted parts is really hit or miss.