I went to the department store w/ receipt and they looked it up and said it was purchased there. I don't understand.
You've been scammed. You have a fake bag. What else is there to understand?
Where did this bag come from? Which department store did you go to? Did you show the bag in the photos to the same person who supposedly pronounced the receipt authentic? Why haven't we seen a photo of the receipt? Where was this bag supposedly purchased according to the receipt?