Hi all, Sadly I am down the back of the bus on an upcoming long haul

. I have reserved 16B/J which in the 77S are aisle seats in front of WT cabin. 16A/K are sky cot seats. My departure is Wednesday at 18:30 and although the seats are showing as available on MMB I can;t move my partner or I into either of them. I tried calling BA and they say they are available but I need to go to airport to get these seats. Is there any chance they will be available to reserve before then? Maybe T-48? Cheers in advance