That sounds like bad customer service.
May I suggest that you copy the passage you wrote here and submit it to Dior customer service here:
https://www.dior.com/couture/en_int/contact
Since you already took the time to share your experience, you should let Dior customer service know. They will speak to the associates, and better yet, they may even offer you something. It's up to you, but I think it's important to let them know this. This is especially since you bought something.
I would love to see what you got!
Which colour and material of the medium LD did you get?