Had some really good experiences with customer support recently.
Booked directly with HAL, so without a TA. But every mail I send to HAL Customer Service was always answered within a few (working) hours.
From name corrections, cabin changes to dining time changes (They even already booked a table for 2 at the window when I just asked to change to Early dining!). Everything was handled quickly and expertly.
There's still more than 250 days remaining before my cruise begins, so I do feel a bit silly for bothering them with so many questions so soon, but they don't seem to mind.