I'm curious about point #4. First of all, when I make a booking, admittedly not six months in advance, it tells me what seats have been selected for me by the computer. So even with three PNRs, that would set off alarm bells. What am I missing here?

Secondly, if the flight was oversold, it would have been hard for the flight attendants to seat you together. A group of five is tough. What were the different locations in the plane to begin with? Were you in five distinctly different areas? Over the years I've had flight attendants try to accommodate people that had separated seating but wanted to be together. It's understandable with small children, less so with couples that can't stand to be apart for a few hours. I've been asked to move, and generally agree unless I am being asked to give up an aisle for a middle seat as I hate stepping over people to go to the lavatory. Lots of regular fliers are the same - often accommodating when it is no skin off their back, but less so if it means an effective downgrade in convenience... or if they are comfortably settled in and working/reading, etc.

It's not easy for the crew to find five abreast seating. You might find enough people willing to move to get, say, three or four abreast, but a fifth person might refuse. For people on different locator numbers, this almost always has to be sorted out before you get to the airport. By the time you get to the airport even a flight that is not so heavily booked, say, 80 percent booked, will usually not have five abreast seating open. That's because as people book their seats, or check in, there is a run on window and aisle seats. The airline's computer also distributes seats in a deliberate manner for weight and balance considerations, which are critical.

There is no algorithm in the central computer that anticipates you will want five seats abreast, and with the oversell situation, you're expecting a lot to expect the check-in attendant, gate attendants or even flight attendants to sort this out to your satisfaction.

I'm sorry about the other points, or the tone of staff, it's like other people here have said, this is one of those situations you'll avoid next time no matter which airline you book, and the people here have given some very useful tips

In a situation like this, a transpacific flight, I'd even suggest paying for priority seat selection at the time of booking, because even the day before a heavily booked flight it's probably too late to expect five abreast seating to be available on most flights.