I am sure a main dealer will organise a new parcel shelf for you. I bought a new parcel shelf for my new-to-me GT from the main dealer in Reading back in July - the one the car came with was dented and had gone all 'furry' on the top - not nice!
A new parcel shelf really smartened up the car, along with new internal trim to the boot lip (broken inside), new sill liners for both doors (the 'kick plates' on old ones were really scuffed) and touching up some minor nicks and marks on the leather seats and door cards. And I'd recommend a genuine Alfa semi rigid boot liner, which is very reasonably priced and available via the official Alfa accessories website.
Well worth the outlay!!