Were you on the flight on 14 Dec? I was supposed to fly that day but it got cancelled (delayed 27 hours) and I ended up flying with China Southern and had to buy a new KQ flight from Bangkok to Guangzhou! I had a connecting flight on Xiamen which also got booked in a different class and I had to buy a new ticket for that too...
And mine, VN has not posted yet and retroclaim doesnt work for that!