Nikon´s UK service centre, based in Richmond, London, are excellent. I´ve had stuff repaired there. They charge a "flat" rate for servicing if the damage isn´t covered by warranty, and will assess the cost for you first to see if you want to go ahead and pay.
In my experience they are 'OK', but I wouldn't go further than that. About 18 months ago I asked them to supply me with replacement rubber eyecups for my 8x32 HGs. I wanted two pairs as they seem to distort quite quickly. I also wanted a pair of replacement plastic labels-the ones that say 8x32HG etc as they just fall off in normal use.
At first they wanted me to send the bins in (!!!) but I said I could fit them on my own, so they agreed to supply one set of eyecups free of charge, but not a second pair as they were in short supply! The labels they supplied were for the 8x42 bins, so no use! Doesn't inspire confidence does it?
I also remember several people on BF having problems with the tripod threaded inserts on their ED50s a while ago. Some were charged around £50 and some were fixed for free under warranty. Why some and not others?
To my eyes both of these issues (tripod threads failing, and scope splitting in two) are clearly warranty issues as the item is not fit for purpose if you cannot screw it onto a tripod or remove the eyepiece without breaking the scope. Obviously Nikon's service centres come across a variety of user-accounts as to how faults occur. Some will no-doubt be clear-cut cases of faulty products, while others will be from less than honest users who are trying to pull a 'fast one', and they have to decide on an individual basis how to proceed.
Perhaps a carefully worded letter to them, explaining how this happened might result in them 'doing the right thing.' Afterall, this is not a cheap bit of kit that you want to throw away and forget about. Perhaps also worth mentioning that this is being followed by many other users on a popular internet forum!
Just for the record Chris, exactly where did your scope split. Did the scope crack or did two parts of the body come apart along a join? Just interested, and also a little concerned about mine.
Steve