I did try this in the end. I submitted the form on the 14th (first day for Diamond) and waited... on the 16th I missed a call which came in after 10pm and I was asleep, they tried again a few days later while I was in Macau without roaming... and a few days after that when I was in a gym class. After the first call, I tried ringing back. After 45 minutes on hold, I got through to an agent who had no clue what vantage pass was. After the second missed call, I tried whatsapp - and they just said there was no availability on the flights (it was the 18th by then). I tried a few other dates - all zero availability. Gave up in the end. When I FINALLY got a call from the original form which I answered, it was about 30 minutes after booking with another airline for the trip I had been trying to get on Cathay, so I used the time to berate them for their process. IN WHAT WORLD is it a good idea to "fill in a form and then wait for a phone call"?????? I get about 1 phone call a month - NOBODY uses the phone these days - and certainly not without scheduling a time first! Cathay are still living in the 1990's. Anyway, I found the whole process to be an exercise in massive frustration. And yet another black mark against Cathay - they are accumulating black marks like a black sheep right now. Sad to see a once great airline fall so far. Their customer service makes Air Asia look good.