I'm not complete certain about the situation, but 
I don't see anyway why you can't confront the 
seller first. Especially, if they didn't metion 
the damage when they sold it to you. 

Well, this is a tough situation! I have been 
there done that too, but it wasn't a dream cel, 
but still it was a pretty expensive cel. At the 
end I just had to let it go, because it was 
bothering me so much. I didn't care if I lost 
money in it, I just wanted to move on. 

Like you said, to restore a cel that much, it 
would definitely reduce the value, and at the 
same time the thought of it was once a damaged 
cel will stay on your conscience. 

It's really up to you, but my first suggestion is 
to go with C (confront the seller)! Sorry this 
have to happen! Good luck!

-manslayer