Took me a while to book two between HKG-LHR for my wife and me. Many choices out of HKG, but most of time you need to select work days as outbound date to see the 70k miles bargain deal pops up.
Since the SEN companion awards do not work for mileage bargains, I have to take some advance from mileage (30k).
1st time booking did not go through, and the service line lady confirmed me (after asking supervisor) that mileage advance won't work for bargains. But 5 mins off the phone, I refreshed the webpage, and it went through with around 30k miles advance
