Sad to say but you were told right. Nuova Simonelli discontinued that model between 2005 and 2010. After that parts that are on the shelf are quite literally first come first serve. I say this because it was about 2 years ago when I ordered the second to last boiler for Premier line. If NS doesn't have one your pretty much up a creek unless some repair shop just happen to stock it. Chances are they don't. Those boilers are pushing $1,000 new so most people tend to order them from NS when the need arises.
If you can take your boiler out and acid bath it it might be possible to find a welder who is willing to try to patch it for you. I will say of all the patches I've seen none of them have ever held more than a couple of years. There is a reason why your boiler has a hole in it and its usually water related. I would suggest you find out how hard your water is along with the PH and hop back on here with the results. We might be able to help come up with a plan to keep your next machine from chewing through its boiler.
