Wedding 5 weeks away and i hate my dress! Help!

When I bought my dress last year, it was marked as "limited edition". I asked what that meant, and they said that it means it's discontinued and will no longer be made. The dress is champagne coloured; and I went in wanting a white dress. I was hesitant on getting it because of the colour, and I told them it was perfect (it was, besides the colour and the size) but that I wish it came in white (the champagne was pretty though). They said "it did come in white, but is no longer being made as it's discontinued". The other issue was that it was a size 12. I'm a size 2/4 in dresses. But they said it could be sized down to fit me. I also tried on a petticoat with it and decided I wanted a petticoat to fit under it, and they said that it could easily be done by opening the seams and adding a bit of fabric (the owner of the bridal shop told me this). So after spending 4 hours there, I bought it (part of buying it so quickly was the fear of not being able to get it if I waited, since it was discontinued).
A couple of months later, after the dress was fully paid off, I had my first alterations appointment. They told me that since the dress was discontinued, they wouldn't be able to get matching fabric anymore to add to accommodate the petticoat. So the seamstress that works there said that she needed to replace the ENTIRE underlaying fabric to accommodate the petticoat. I was pissed, as I was told BY THE OWNER that they only needed to open up the sides and add a bit of fabric. I had to pay her $500 for the cost of the extra fabric and alterations. The new fabric is heavier and doesn't drape as well around the dress, as the original one did, and the waist/drop is different than how it was before because of the thicker (and excess because it was a size 12) fabric. It doesn't even look like the same dress anymore. I hate it.
The other issue is the petticoat. The one I tried on at the store with the dress I picked out last year was soft and flowy. They ordered me the exact same one, however, they failed to mention that the new one would be MUCH poofier and MUCH more stiff than the one they had for people to try on. The one they have at the store is several years old and has been worn and washed countless times. The brand new one I received completely changed the shape of the skirt on my dress. I was not happy and immediately brought that up to them. I was told we could cut a layer out of the petticoat to make it less "full", so we did, but the actual shape still didn't change. With the "worn-in" store version of the petticoat, it made my dress have movement and created nice flowy pleats in the skirt. The new one caused my dress not to be flowy at all and made the top layers of the dress look tight and stiff. The seamstress steamed each layer multiple times and even ironed it, to help smooth it out and flatten it, but it didn't change the shape or much of the poofiness. I begged them to let me switch out the new petticoat for their old one, and I was told that since a layer was cut out of my petticoat, they can't exchange it. I then offered to buy a brand new one to give to them in exchange for the older worn-in petticoat, and they would not do so.
I would classify this as false advertising. Had I known that their petticoat was years old and has been worn and washed many times, compared to the brand new one, I would not have gone with this dress. We've been trying for months to wear it down/flatten it to no avail.
When I went in for my last fitting the other day, I was looking in the mirror at my dress on (hating it), and glanced over to my right and saw MY dress on a mannequin, but in WHITE (which is the colour I wanted, but was told the dress was discontinued) and it was in my size. I was so angry and I said sarcastically "I thought my dress was discontinued?". They said "it is", and I pointed to the dress on the mannequin and have a 'what?' face. They didn't really acknowledge me and walked away. I am so pissed off.
I spoke to them later that day and said that I am not happy with my dress and asked again if we could switch out the petticoat (though idk if that would solve the issue of the heavier fabric that was added). They said they would let me have the old one, but I would have to pay for the replacement of a brand new one for them. It's total bullshit, considering the one that I bought (even with a layer cut out) is more ACCURATE to what the real one is really like than what they have in-store for people to try on. Honestly, they should have a NEW one in stock in their store so that people can see what it really is like. I felt deceived with their old petticoat.
I hate my dress. I am SO tempted to just buy a new one (it's $2200 after tax) in the right colour and size (even though I don't really have the money... I'd have to sacrifice buying other things). 😭
What should I do?