I don't think you can return Chanel to stores that don't sell them either. Not sure which shoe you are looking at but here is my experience - I am pretty much a true 8 1/2 with medium width, my feet are not wide.
For the all Chanel all patent flats, I found the 8 1/2 impossible to wear, needed the 39 - they shipped from another store and the 39 fit. They fit snug but they "warm" as you wear them and the snugness was fine. I say this because if you have a width issue, I would even go to a 39 1/2, or full size up, by comparison.
For the soft leather with patent captoes, I could almost wear the 38 1/2 but the 39 was so comfy I went with them and they feel great. Bummer thoough because the pair I'm going for next will need to be shipped from another store. The soft leather has more give so if borderline you may find the soft leather to be true to size.
For the Cambon flats, same as the soft leather. I haven't bought them yet because I really want black/black but still a 39 for comfort.
Here's the kicker, the black and tan flats with the mary jane style. Interesting that even though the leather is soft, it had a patent trim around the top of the shoe instead of the soft trim the other soft leather classic Chanel flats have. These ran very small for me, I would have needed a 39 1/2 to even a 40 on these. I had to pass on these and they were marked to $317. from $635. Grr. It's a plot - Chanel always makes sure I pay full price
