Recently moved from bronze to silver, and had a similar issue with existing bookings. Thought I'd share an update on the current state of play.
In the end it took 12 days from receipt of the "Great news, you've upgraded" email for me to be able to select seats on existing bookings, surpassing even my own already pessimistic expectations of British Airways' IT.
Last edited by markle; Dec 12, 2025 at 6:02 am