一定要在28天內完成體檢
you must complete your health examination within 28 days
If you are unable to complete your health examinations within this period,
you must contact the Working Holiday Visa Processing Centre
and provide reasons as to why you are unable to do so.
u may~
google Aust. working holiday official website online service ,
to see if there's any overseas office settled in HK,
get the contact phone number or email,
then , give them a direct call to ask for their help ,
that will be the most efficient way for your emergent question~