Got a delay notification for the KA HKG-HAN which was roughly an hour. Contacted Cathay via Twitter and said the delay is going to cause me issues with my connecting flight on a separate ticket and that they should take me off the flight as I'll try and organize a new ticket from HKG to my final destination.
They replied:
Thanks for confirmation. We will uncheck you but please note that there is no refund for your ticket and you will have to forfeit the last sector.
I wouldn't have taken this flight anyway but I thought it's a good - clean - excuse not to use that coupon and to formally notify them. At least with Twitter there's a record of it should there ever be any dispute about this.