Strange as it seems, you can order the "original" parts from Porsche and they have them ready to deliver. Ask me how I know...
If the mechanic was not a dealer, and they didn't charge a significant amount of labor for the arbor based update, I don't know that you have a recourse with them that doesn't include $ out of your pocket.
As for doing the job outside, I think the weather in San Jose would lend itself to this!
Good luck,
Chris