Filter
I have just changed the pollen filter on my Marea Weekend. Not sure if it's the same on your car though, but here goes.
If your car is RHD, open the bonnet, on the passenger side, below the wiper, there is a plastic cover about two feet long by about 3 inches wide. Remove the two screws either side and you have access to the filter. It is a bigish beast about 12 inches by 7 inches and about 1 inch thick and is held in by an elastic strap. I got my replacement from a motor factor at less than half the price of a Fiat dealer.
Cheers