Wedding Dress Issues

Hi brides and wedding wire, my wedding is in a month and the store where I ordered my dress insisted that they should not do my dress fitting in January. The store insisted it was too soon an that they will do the fitting in early March. I got there 2 days ago like they said and the store had ordered the wrong dress (4-5 sizes too big) They then pulled another dress size off their rack and claimed it was just a mistake in bagging the dress, but that dress still was not my size (3 sizes too big). They then proceeded to tell me that the reason the dress did not fit was because my body proportions are all wrong. Nearly in tears, I told them That this was not the right dress. The MOB had a good conversation with them after which they agreed to get in a new dress. They can’t guarantee when the new dress will come in. They first said it would be in a week, but then they said they can’t book me for a fitting until 2 weeks, and that alterations would take them a week after that. Which means I won’t have a dress till a week before my wedding. You know if things go as they even planned. I am so very stressed and don’t know what to do. I think I should start shopping for a backup dress off the rack potentially? I am worried this store is disorganized and well mess this up again! Any ideas?