sorry but are you saying Asiamiles/CX levied the "foreign transaction fee" in their favor? I would assume any such fees are levied by your Card Issuer so if you like any remedy you have to consult your card issuer.
don't forget to complain about the unfavorable USD/HKD FX rate when you call

i'm not surprised if you are ripped off nearly 1% on the FX even though both currency are supposedly 'pegged'