I can imagine how stressful this would have been. But it's fair to ask, did you ever actually call and explain this situation to a human being over the phone, or for that matter specifically ask at check-in or at the gate? From your description, it sounds like you might have been doing all of this exclusively through the website. Others will probably know better than I do, but it's possible that a human res agent might have been able to open those seats for you. We certainly hear a lot here about people reserving bassinet seats in F and being warned they might be moved if a baby shows up. Since your row numbers make it sound like you were on a 77A/77D, the bassinet seats are not ELR for sale so that wasn't in play.

Not trying to blame the victim. Just making the point, learned from experience, that even in the internet age it's not always best to assume we can do anything and everything over the web. For better or worse, sometimes there's no substitute for speaking to a real person at the airline.