Sorry to bump an old thread, but my issue is almost exactly the same so I thought it would be better than starting a new thread.
Issue:
Traveling LHR-HKG, 5th October 2016. (less than 24 hours now).
I tried to choose a seat last week but they wanted $55. Not it's less than 24 hours, i have done the online checkin, and they allocated me a seat (one of worst on he plane).
I am trying to change it, i have the option to input my choice, I confirmed it wasn't occupied, but I get the same error as mentioned above:
We're sorry, the seat(s) you have chosen are not available. You are still shown in your original seat(s).
I called them up and they said, sorry, we can't help you if it's less than 24 hours before the flight.
So bloody annoying, anyone got an idea?
I think that is true for any airline that with <24 hours to departure that it is handed over to the airport to control from then on in. I think the only chance would be to try and get to the airport check-in desk via phone or get to the airport very early and see if they can change seats. Good luck.