i know it's abit late, as the 3 days you had left are almost gone, but there's a list of shops grouped by postal code on this page:
http://www.hochzeitstipps.ch/adrkleider2.htm#08

by the way, i have seen that C&A also has wedding dresses and accesories ... dont know exactly what and how the quality is, but it's maybe worth checking it out, if you want soemthing fast and not too expensive .....

I'm also on wedding dress hunting, but have a bit more time ....

Good luck!