Why should BA rebook to a indirect routing let alone rebook OAL when pax have already been rebooked on a perfectly suitable flight less than 3 hours later (albeit in WT). BA is at liberty to downgrade if deemed fit (against 75% refund of the fare for that segment of course) and the OP has been rebooked to the a new BA flight and to arrive within 3 hours of the original; you hardly can't expect more from BA in a situation like this IMO.