Shortly after booking my original LUX flight was cancelled and I was booked onto one the next day, I rang up BA holidays and asked them to move me onto the later flight on the same day as the original flight instead, and to extend my LUX hotel booking by a night and move all the other flights on by a day as well. They did this with no worries. I had all the flight numbers, times and what I wanted ready before I rang, so it was just a matter of typing it in. I got through to BA holidays very quickly on the phone and the lady I spoke to was very pleasant. However once the confirmation of the change came through it was apparent that my re-arranged LUX flight was now in Y so it required another phone call to get that put back into CE.