I just saw this. OMG...I am so glad that O will be ok. Did you take lots of pictures of her injuries? I would ASAP before they start to really heal. What a stressful time for the whole family! I can't believe that the neighbors haven't come to check on her and make sure all was well.
I would be LIVID as well and probably want to kick their a**es, but emotions aside, there IS a way to fix that fence...just get some long screws and screw in a fence plank or call a fencing company to come out and fix it. Is it your fence or theirs? If it is yours, you will be responsible for fixing it. If it is theirs, it will be their responsibility. I don't know if you can sue them but you can certainly file a formal complaint against them. The problem is, that if that GS is deemed "vicious" then if it is taken from them it might be PTS without any attempt at rehabilitation, which is only hurting the GS as well. So you have to decide if you are willing to take it to that level or not. I would also think (keep in mind, I am not an attorney either!) that if it is your fence, they may not even be responsible for the vet bill, though if it is their fence, it is possible that they could be held responsible because they did not maintain the fence or fix it when there was a clear issue shown at the beginning.
At any rate, please give her big huge kisses from us and *hugs* to you, your hubby and Vegas. I hope she heals VERY soon that poor sweetie!