I have had my flights to Japan moved from late morning to early/mid morning in April. BA have asked that I call them if I wish to change flights and I noticed that there is a JAL option going from T3 which would work better for me as it means I can stay in a hotel which is connected.

This particular flight does have a BA flight code. Does anyone know if there is anything I can do to move to this flight as they have initially said no.

TIA for any replies.