Made to measure bridesmaid dresses that DON'T fit!?

Hi Everyone - Im really hoping someone can help me! Im one of three bridesmaids & we have a problem! Our dresses were purchased from a bridal shop in Reading, Berkshire but were to be made in China. We had our measurements taken in early February & our dresses finally landed yesterday. The material is lovely, the colour just as the bride wanted, the stitching is perfect ... problem is THEY DONT FIT! They are in no way, shape or form 'made to measure'!! The smallest bridesmaid has put on about 4lb since February, she was worried her dress wouldnt fit ... its hanging off her - the bust is way too big. Me (the middle one) have lost weight & inches with a personal trainer - my dress will not go anywhere near me - the gap between the two sides of the zip on the back are about 6" apart ... the other bridesmaid who had the biggest measurements, has lost 1 1/2 stone since February her dress only just fits (she thinks its too tight) and its about a foot too long!!! What the hell are we meant to do? to top it off, the bride wanted a shoulder piece on the dress (hard to explain) but basically a piece of material fixed from the bust going over the shoulder & fixing on the back ... she specifically said how wide, where abouts from & too ... the dress arrives with a rectangular piece of material that HOOKS on ... at no point did she ask for it to be detatchable! She is devastated, okay yes its all fixable (using a different seamstress) but its not the point, they are not made to measure, they are not even how she asked for them to be! to make matters worse, the supplier, a very agressive & unapproachable woman is refusing to speak to us saying she told us they would be unchangeable or refundable as they were made to measure. The bride does have a contract with this woman but as the dresses are not "fit for purpose" is there anything we can do? I personally would be demanding a refund as I wouldnt trust her to make the alterations! If anyone has any advice you could give us we would be eternally grateful - thankfully the wedding isnt for another 8 weeks & the seamstress we know is a lovely lady & says she'll fix it no problem but that doesnt mean this other woman should be able to get away with something like this! I really hope someone can help & look forward to hearing from you. Many thanks