i think you are correct. they are going to have to take the whole rear end apart and start measuring everything... in the end... i think they should put it back to stock and i think that would take care of it. but either way... they need to start measuring.I'm glad to hear that you're on the way to a resolution.
They'll probably be stumped too. The best way to really figure this out is take it all apart and start measuring. Essentially starting all over. And they'd probably need stock parts, or another 959, for reference.
I bet they'll cut their losses, buy it back then auction it off.
I'm really hoping they go that route instead of throwing some gnarly spacer on the back and trying to pass it off as fixed.