They can't do anything about that. What they CAN do is not service any item that's been redyed or altered. Chanel has no relationship with any consignment stores, and has no legal authority over goods sold UNLESS they are selling overtly counterfeit items.
Yes that's what I thought initially. Then I thought maybe they used the fact that the copyright belongs to them but I emailed Chanel to check. I was given the same reply as you guys have stated above.
So I guess I was right then. VC's authenticators have been screwing up and then covering their tracks.