No there is a desk on the port side of Windows Cafe deck 9 which is staffed 10-1600 each day. In addition on embarkation day they are there from 12 and often also have a second booking station set up on the Pool Deck. You are far more likely to be successful with reservations if you visit yourself. On embarkation day you may not see your butler until late afternoon and a lot of guests will already have made direct bookings. Its an Urban myth that butlers have access to more slots than the reservation desks