Oh thank you so much for telling me this!Don't go there - unfriendly people. Maybe they expect you to buy nothing less than 100k EUR. Better walk a few 100 m to the one near the Opéra Garnier. Sorry I did not remember the nice lady I talked to 2 weeks ago.
12 Boulevard des Capucines, 75009 Paris
I would propose buying your JUC there and walk over to the Place Vendôme afterwards just to have a look proudly wearing your new JUC.
I will walk to the store you talk about. Hopefully they have all sizes in stock as I really have no clue.