Whilst the web-site worked perfectly for me today when placing a duplicate booking for a BAH to KUL, even allowing me to select alternative times for the domestic flight (page crashed when tried to do that a month ago for the original booking) ...

one advantage of the BA IT was, despite cancelling the original booking; was still able to go to the cancelled booking on MMB, move us from the 2nd Row (WTP) seats we had - then go into the new booking and place us into the now empty 2nd row seats