When they change your aircraft??

We fly next Saturday 23rd to Jamaica and the seat plan still shows the old heathrow 747 (all upperclass in bubble)
I know that the plane is now reconfigured so I'm waiting for the seat map to change.
Do they accomodate your existing seat preference to the best of their ability or do they just evict everyone, so it's a mad rush again.
We have 2 x 2 at the back of economy, if we are evicted we'd like to try to upgrade to PE at the airport (although I think there are only a few seats left)
I'm really not keen on the ones in the middle
We've usually either flown PE or had the planes with the extra legroom seating which is always great value for money
I know that the plane is now reconfigured so I'm waiting for the seat map to change.
Do they accomodate your existing seat preference to the best of their ability or do they just evict everyone, so it's a mad rush again.
We have 2 x 2 at the back of economy, if we are evicted we'd like to try to upgrade to PE at the airport (although I think there are only a few seats left)
I'm really not keen on the ones in the middle
We've usually either flown PE or had the planes with the extra legroom seating which is always great value for money