The Dress for the Bal du Bac

hi I am looking for ideas as to where to search for a dress for my daughter's graduation ball. Online buying is out, as she does not have a regular figure and I couldnt be bothered with all that sending back the dress etc. If anyone can name a few shops for me that stocks those kind of dresses, will you please let me have the info. Live near Tervuran and will travel to Antwerp etc if needs be