The 169 is notorious for uneven tyre wear.
Most of the time, it's due to rear beam geometry issues. The factory tolerances are extremely wide, and many beams are outside of those tolerances even when new. Lack of any easy adjustment options doesn't help. Back in the day, quite a few out of tolerance beams were replaced by Fiat under warranty.
If you're serious about trying to tackle this, the first step is to get the rear wheels aligned with the centreline of the car. If this isn''t correct, no amount of front toe adjustment is going to stop the uneven tyre wear.
If you've just replaced the beam and the bolts aren't corroded, you might get some adjustment from the bolt holes by loosening the beam. Trying this on a 10yr old car that's never been touched since it's left the factory would be a nightmare.
After that, you're down to improvising with homemade shims.
Another issue is that the rear beam can get bent out of alignment; two easy ways to do this are to slide the rear end into a kerb or use a jack in the middle of the beam to lift the car.
One more way to get the front alignment wrong is to install the top mount rubbers (the ones inside the wing) the wrong way round.
My own gold standard for Panda wheel alignment is no uneven tyre wear over a considerable mileage. If you are lucky enough to have one which isn't wearing the tyres excessively or unevenly, don't let anyone mess with the tracking.
Also there are plenty of places out there that have expensive, sophisticated 4 wheel laser alignment kit, but lack staff with sufficient knowledge to use it correctly.