-------------------------------------------------------------- I was wondering if I could look up the key code by the Vin number, not sure.
I’ll probably call Auto Ricambi. They are very knowledgeable and helpful..
Auto Ricambi stock key blanks and trunk locks, in case the locksmith doesn't have suitable one's on hand. Iirc, Auto Ricambi also have info on which key blank/s should suit your car year.
If you can get the trunk open and remove the lock barrel (the part the key goes into), there might be a key number stamped into the end - the locksmith might be able to use this no. to cut a new key (iirc it's a 4 digit code).
Did the garage lose the door key also? Sometimes the door and trunk keys are the same?
I'm surprised your garage is having difficulty in opening the trunk lock - have they not got a 'Lock-Out Kit', lock picks or better yet an 'Unlocking Gun'?
(this has a small probe, which, when inserted into the lock barrel and the trigger is pulled, cycles the lock wafers to open the lock (similar to picking the lock but much faster).
Even without these tools, opening the trunk lock shouldn't present much difficulty. With old Fiats, you often find that some/all of the lock wafers (the parts which are lifted by the key so that all of them are level with the barrel allowing the barrel to be turned) are seized in the open position due to lack of correct lubrication, so no key is needed, just a screwdriver to twist the barrel. I often found that trying a few different keys and jiggling them in and out (i.e. raking the wafers) would open the lock. If this failed, I used a small screwdriver to maintain a twist on the barrel while raking the wafers with a piece of bent wire, usually worked.
As you have an original ignition key, you should be able to get a copy cut. (Auto-Ricambi stock blanks for ignition keys also).