If you continue to struggle, you might try:
High-quality car parts and accessories from the experts - buy now here. 24 hours shipping + from 50 Euro free shipping - Your online shop of the Augustin Group
augustin-group.com
..who appear to be expecting stock, and
will ship to the UK.
Not a cheap option, but it might be a hard-to-find part.
(There is a post somewhere on here, that I can't vouch for, that identifies Iveco 500377827 as the identical part. It doesn't appear any more available than the Fiat number, but might provide another option).