I booked with Viking Australian office. I said I would use flyer points to get an upgrade, which should be possible as I was booking 8 months ahead. The 'manager' seemed quite helpful.
Closer to the cruise date my wife had a back problem. Her doctor said she should not travel long distance without being able to lie down. So I asked Viking for help. The Australian office contacted HQ but they said no. It was then that I discovered that the Viking flight tickets are 'O' class. That's how they get the cheap airfares. Trouble is, there's no changes allowed. None at all. Of course, it's all there in the fine print, but I was relying on the fact that the Viking guy didn't mention this at the time of booking.
So my wife had to fly business class on a different airline to get to Rome via Hong Kong, while her Viking ticket was wasted. However, my wife's seat was sold to someone else for part of the way. My complaint about the no-changes-to- flights received a response that the agent had fully informed me. He had, but only when I asked for help, not at the time of booking.
Very nice indeed. Very clever shower cubicle.