I would call them. I just checked searched my email trash, and six times this year I traveled to Italy with confirmed reservations at a hotel, but four times the hotel did not have the room when I got there.
Both times I didn't even get notice that the room wasn't available until I was already in the air on the way there. I've never gotten a good explanation for this. It seems to just be one of those Italian things.
The most common explanation I have gotten from hotels when I squawk about it is that they don't manage the reservation websites. They are farmed out to several different travel websites that don't communicate with one another. The front desk just gives a shrug of the shoulders and says they don't manage the websites. I'd call them and make sure you have a room.