Shadow Ghost Women's Halloween Costume

This Halloween costume was only worn for about 5 minutes. The outside package says size 14/16 but when I opened it, the tag said One Size Fits Most. I was able to fit it up around my waist, but it was to small for my chest (DD bra size). While it isn't small, I cannot say it's a true size 14/16. Unfortunately I paid full price without asking the seller to open it so I have a Halloween costume I can't wear! This costume includes the dress, a veil, and a cloth corset that ties in the back. It's in perfect condition. No tears or any defects. It's all black with some silver trim.