Wedding Gown Nightmare

Hello all, I'm on here to seek some opinions. My wedding is January 12th. The gown came in mid December and when my consultant helped me to get into it, it was too small. She assured me that it was an easy fix, saying I only lacked an inch or so. She pointed to the sides where I could have it let out, and advised me to try to lose a few pounds until the seamstress could get to it after Christmas. Then she reiterated that same message to my mother and hurried me to the counter to sign off on the NO RETURNS EVER policy. I was irritated but thought I would just have to lose the weight that she thought I must have gained and get over the cost of alterations.

I should have seen it coming. When my seamstress saw the gown she said "no, that's not going to come out enough to make any difference, but let's see you in it and decide" so for the 10th time I did my best to get the zipper up and for the 10th time is stopped short right above my waist. (Side note, my self esteem is dead and gone). She came in to see and when she walked behind me she gasped. She told me there was nothing she, a 40 year veteran in her field, could do for it that would turn out nicely.

Long story short I was advised by the shop against my better judgement to order a gown sized 6 when I'm a street size "7." The consultant never felt the need to tell me that I ought to order up. She didn't feel the need to tell me that this gown size "6" would more likely be snug on a true 4. She did, however, try to quiet and calm me by lying to me about how "fixable" my dress wasn't. And when I marched back into the shop (over an hour from home) to let her know that I had caught on, she told me that my best hope was to rush it to the tailor affiliated with this shop and have them put in an external corset. I do not want a corset on the outside of my dress. I want a gown that fits and that's why I took the advice of someone who orders gowns for a living. I went to the tailor anyway and was told that they would need to add 8 inches at the bust! An external corset would destroy the look I'm going for and everyone in my family would hate it! (no offense to the brides who like them, that's just my family!!).

I have 6 days and very few options that I'm liking. What do I do? Buy a dress off the rack at another shop? Demand that the original shop give me a sample size that either fits or is just a bit big? My seamstress will rush to take it in for me if I go that route. Do I seek a refund despite their policy and buy another dress in the meantime? I was ill advised, lied to, and now I am one week from my wedding and don't have a dress. They've caused me so much stress and pain but all I really want them to do is make it right so I can move on with my wedding. They don't care that I don't get to wear my dream dress at my wedding. They don't seem to care if I have a dress at all! Additionally, they did not like my idea of exchanging my brand new dress for a sample that has been dirtied and tried on excessively. Please help!