I called BAEC today and explained that due to the schedule change (and change if aircraft) I wanted to change onto the BA flight out of MIA. The agent said that sheets the schedule change being only 25 mins I couldn't change flight. I explained that the aircraft change meant I wasn't getting a fully flat bed as per original aircraft. He was checking the aircraft config seat map then asked if I would mind holding to see what he could do. I was on hold for about 5 mind then got cut off !! Arg. Called back but waited too long and had to go to a mtg. Will try later !