Q. How much patience should I have with my local dealer?
A. Zero
Document everything, file small claims case, move on with life and enjoy your bike to the extent that it does not absolutely require an authorized dealer for repairs now or in the future. The 2015's can be particularly reliable once set in good working order.
I do feel ill saying this but the situation hasn't really changed in 10 years for Zero Motorcycles owners. The dealership model remains a dumpster fire. Anyone with enough competence to work on your Zero Motorcycles bike at that shop will get hired away to some other shop within a few years time. Zero Motorcycles has held steadfast as being against right-to-repair and if we're being honest just plain anti-customer once out of warranty.
You've got an awesome rad motorbike and some punk moto mechanics stripped your seat bolts and again dropped it off the motorcycle stand?
Been there; loose axle nuts, missing seat bolts, loose handlebars, a different customer's wheel installed on my bike "It's not like we ever thought there would be two Zero bikes in the shop on the same day?"... The only honest and decent moto mechanic I've ever known to work on my bike was Steve. Zero told Steve he's not allowed to repair/replace the encoder on my bike's motor for a quick turnaround. "Why?" We never found out why. The bike was in shop for a month waiting for a whole replacement motor. Zero refused to say what was wrong with the bike that time. Steve told me it was completely obnoxious the way that Zero treats trained service professionals and treats every interaction as need-to-know and they won't tell you even when you need to know!
Out of warranty I had to take to bringing my own tools and hand over the bike (2016 DSR) ready for the service tech to plug their world of warcraft or whatever-the-shit Zero has their remote diagnostics and commissioning software running on, and then re-assemble my bike after.
I raised this point with people at Zero HQ before when they had a little pow-wow asking what we wanted. I said, tools and access to parts (this was before the glorious and wonderful AF1Racing offered their catalog of Zero parts online to the world) to maintain the bike would be nice at any price, or working some kind of legal structure out for a local motorclub to obtain tools and certification to use them correctly for the community. "There's hardly any maintenance, so you have that already." No no I am talking about the dealer cables and access to parts. "Yes, those are for dealers only and you are not a dealer."
And then what happens when my dealer is dishonest and awful, or just does not exist? "We have a training program in place for certified dealers and are adding new dealers all the time." This goes on and then I keep thinking what a wasted opportunity!