They do the online Disney Store exchanges at a mall Disney Store. Just did one on Wednesday.
from the
disneystore online site:
Returns or exchanges can be made in any US Disney Store location, excluding Personalized Items, Art, Collectibles, Disney Parks merchandise, Mirrors, Electronics, and Indoor and Outdoor Furniture. All returns must have the original packing slip/receipt with the merchandise to be returned or exchanged
to OP you can see they exclude Disney Parks merchandise.