Originally Posted by
S_W_S
My first thought as you mentioned booking by phone, is that this has had to be sent off to be ticketed.
If your booking hasn't been ticketed yet you won't be able to select a seat.
If you go into the flight details page in the BA app right at the bottom there is a ticket number field, if this is blank then that's probably why.
My flight has been ticketed. In past, when booking on ba.com I was able to select the seats (Silver) during the booking process, even before the file for submitted for payment.
BA.com gives me a message 'online selection tool is not available', you can call us to change your seat. Not ready to spend my life on hold.