So Sorry to hear your news.
your dd sounds like a very bright and intelligent girl who will do well wherever she goes - however I can imagine this is no consolation to you at this time.
The next steps you could consider are an appeal in the summer and apply to sit the 12+. Which area do you live? You could possibly apply to sit a late transfer exam for another area such at Herts or Slough? The other thing you could consider is an independant school. It would take a huge hit on your finances but possibly worth it in the long term. Usually Independant schools can offer bursaries or scholarships for bright pupils like your daughter so worth some research.
all is not lost, dont give up hope just yet...
wishing you both all the very best