IB Flight operated by BA - advance seat booking
I've booked economy seats on IB4657 LHR to Washington Dulles. Flight is operated by BA as BA 0293.
I've tried online and by phone to BA and Iberia to reserve seats, but told this is not possible - can only do it when turn up at Heathrow.
I am BA silver card holder but this seems to count for nothing.
Will I be able to reserve seats 24 hours in advance online via BA website? BA and Iberia seemed to imply not.
I've seen comments about trying to reserve seats via finnair.com - just tried this but couldn't reserve seats.
I understand that there is no twilight book in at LHR either.
At present, it seems that the best I can do is turn up 3 hours before flight to reserve seats at check in. Is there anything I can do to reserve seats earlier than 3 hours before flight?