Hi Welcome to the forum
McCarrols Fiat Artarmon
Peter Warren Warwick Farm
Foley Fiat Professional Carlton NSW
Generally Fiat Professional dealers service charges are in outer space!
South Coffs Motors seem to have a good reputation, maybe a bit too far.
11 Keona Circuit Coffs Harbour South NSW 2450
Phone: (02) 6651 4877
I would check local mechanical shops within your area to see if any specialize in Fiats or Euro vehicles
There is also a Fiat Ducato Motorhomes Australia owners Group on Facebook that has good info on Ducatos & service dealers.
Cheers
Assuming you're in Sydney; from personal experience with three of the only four remaining (!) of the Fiat Professional Authorised mechanics in NSW, I will only be taking my vehicle to Foleys in Carlton for anything required by warranty. Let's just say I've had issues with the quality of the work with the other two, including a formal MTA complaint. Unfortunately, imho the Fiat Motorhomes FB group is not a great indicator, there are many non-mechanically-oriented people on there who would not be able to provide any useful assessment of a mechanic's competency.
If you haven't already, go buy either AlfaOBD or MultieECUScan - I have both, and have already saved myself their cost.
Once my van's out of warranty I'll be hunting for a decent local diesel mechanic.
That list is getting smaller every year, I presume Fiat Commercial are winding down in AU; indeed if it wasn't for the motorhome market they'd probably be already gone.