OMG! Dress crisis! I need support...updated at bottom

Girls I feel like I am going to be sick...

I had gotten my dress off-the-rack. There is very little adjustments that need to be made...just the length of the gown, which right before I gave them any money they told my mother and I they wouold be able to adjust. When I had gone w/ my MOH for her to order her gown they said they had to take measurements of her height then because they had to order the gown adjusted hollow-to-hem because of the detail going around the bottom. They said the manufacturer does this adjustment...it's ordered that way. I too have a lot of detail going around the bottom so I got a little concerned. So, to ease my mind (after a nightmare about it) I called the bridal salon where I got it. Their response was 'I don't know'! I have to bring the gown in today now for the seamstress to look at it to see if it's possible for my dress to be altered by them. The girl on the phone said 'well we can put you in a really poufy slip and heels, maybe that will do it' I told her that I had a full slip on when I tried it on last time and it still is way too long. So now I am so stressed out! My mom and I discussed it and we agreed that if they do claim they can do it, to have the length altered now instead of a couple of months before the wedding so if there is any problems and I need a new dress, I will be able to get one. I am so upset and angry...I love this dress and I spent a lot of money on it. If I need to get a new dress now, then I lost all of that money!!! This is the second time I have called that salon and have had 2 different things told to me.