I had booked a Cathay flight using Qantas points. We received a notification that our Gatwick flight would be reallocated to Heathrow and we would be advised within 24 hours of the change. That was 48 hours ago and I approached Cathay who confirmed that contrary to the email that they will not reallocate us as we booked through Qantas. Just a warning for other point users who may receive similar emails.