score:11
Yes, ITA is obligated to repay to you the seat reservation fee.
ITA's Conditions of Carriage contain this:
3.2 Booking
...
3.2.2 The passenger may ask for a specific seat on board when such is provided by the Tariff Rules applicable from time to time, found on ITAβs Web Site and during the purchase of Ticket, or communicated by Authorized Agents, ticket offices and Contact Center operators. ITA will do everything possible to confirm the anticipated assignment of seats on board. However, in case of substitution or modification of the aircraft which should have been used for a certain flight, assignment of seats may not be assured even though the passenger had received confirmation. For security and/or operative reasons, ITA may change assigned seats in any moment, even after boarding. If the passenger has paid an extra fee to be assigned a certain seat on board, the Carrier will reimburse said extra fee if such seat is not available due to the aforementioned reasons.
(Emphasis Added)