Unfortunately this is a known problem with how Nintendo tracks and authenticates systems with their shop. There really aren't any workarounds, so far as I know.
My solution (and one that worked pretty well, if I do say so myself), is to buy a broken US region 3DS on eBay or some similar site, and swap the motherboard out of that unit into your unit. Then you can have any color/region combo you like.
thanks i read the post as well but i thought maybe ppl have discovered some other ways to do this without using another system
i guess i will have to borrow my friend's 3ds for its NAND