Bumping old thread, seemed most relevant for my question. This is about getting a round-trip miles "refund" for an (unintentional) mixed-class booking. Somewhat pedantic question over 4k Asia Miles, but anyway...

Need to fly HKG-SIN, ideally J class in a few days. Going down one day, back the next (note to anyone on here: using miles for overnight regional trips is great value). HKG-SIN sector cleared in J. SIN-HKG sector only Asia Miles award available in PEY with waitlist for J...(although I class still for sale and PEY/Y widddee open....I tried asking them to contact CX to open a seat, but no luck they won't release for me).

Agent says they will deduct 50k miles for the round-trip J award, and issue return in PEY since no J available. 50k is the round-trip biz price. I told the agent to hold off, how about I just ticket the outbound in J one-way, and wait to book the return in a few days?

My question is, which the agent said isn't possible, let's say I get stuck in J down and PEY back as it stands now. Aka, I don't get J on the return after all. And let's say I booked as two one-ways (30k miles + 24k miles are the one-way prices). Can I claim back 4k miles difference later because 50k miles is what I would've been charged for the round-trip biz class? Right now they're willing to charge me 50k if I book it all together. But not sure this seems in a gray zone for the refund difference rules?

Or, anyone else have any advice how I should be booking this?