Normally you'll see different color/size combinations at other stores. So if you are looking for a color or size that the Chanel boutiques didn't order you would need to call all of the department stores that carry Chanel until you find the color/size you wanted.
However, we have learned that even in all of the U.S. they don't order everything that is available from Chanel Paris. As an example, none of the U.S. department stores or boutiques order the dark brown metallic 2.55 in any size, and some were lucky enough to find/order them from Chanel Canada.