This has been going on at CP Nagasaki for many years. I think they don't open up the calandar for far-out bookings, and they also seem to be fully commited with tour groups or events on occasion. In years past, I've occasionally had to stay at Japanese chains because the CP was not available, but thankfully Nagasaki now has a very nice Indigo (as Nicolas75 pointed out), and the Marriott near the station is also workable.