Well today I read the entire post and saw you had tried Safelite. Sounds like not all Safelite dealers provide the same quality of service.I did try safelite,
I don't know where you are located but I think Some Fiat parts vendors that supply other part for our Spiders can get windshields also.
There is a similar post right now on Mirafiori.com describing replacing windshield procedure. It might b helpful.
I would prefer to find a new windshield. the lack of clarity of old safety glass along with glass pitting would make me len toward new instead of used.