Hello,
There are 6 variants of exhaust for the 2012+ 500L:
View attachment 455388
View attachment 455389
So it's hard to help not knowing which one is the correct one.
What's the proper part number you need to replace?
On the bottom of the forum banner you've got a link to the forum
ePER, the FIAT spare parts catalogue (from which the screenshots come from). You can browse by model and categories, or search with the VIN number, which I suggest (top left of the screen).
Once you'll know the correct part number just look for it over the internet. If the original part is no longer available (but it should, as far as I know the producers should be able to deliver parts up to 10 years after the production has stopped), there are reputable aftermarket part suppliers.