National - International/Europe contract codes for unlimited mileage?

Has anyone found any contract codes that give unlimited (or raised) mileage in Europe? Booking now in Italy and can only find deals that include 100km. I assume my trip will be at least 200km, so it would be nice to have that included. All in, the prices are still not bad, but I hate the thought of each mile coming straight out of my wallet :)
Thanks