Can I please order a space grey trackpad for my iMac Pro?

I just received my iMac Pro and realized I forgot to purchase the space grey trackpad at the time of purchase. I was just informed by Apple sales that I would have to return the entire unit and place my order all over again just to buy the trackpad in space grey. I would understand this if it was affixed to the computer and required me to send the computer back to install but it is a seperate add on item and should be able to ship separately. I will gladly pay any shipping. It seems outlandish that I would have to return everything and reorder. I hope you can help more than what I was told over the phone.

Thanks