Hi Paolo,
I' m an electrical engineer working as IT project manager. At the weekends I support my Z4 friends here in Bavaria.
As mentioned earlier, the new(!) harness part from the left side is,
without any doubt, on one of your pictures. Have a look at my former posts.
It's the upper part on your following picture, brand new, cut off of the original new harness for 1.058 USD/ CAD you've paid for:
Both sides of this harness are connected in the middle (hydraulic pump area) with the salmon relay connectors to 1 piece, see my former picture. That has been cut by your dealer. That's unbelievable!
Mounting both sides takes about 8h, so he avoided an afford of 3-4h.