So unfortunately it looks like now I'll have to change my booking completely.
I just called Qantas - if I cancel my 318k OWA trip altogether, they've advised that a 6k cancellation fee will apply, and 95% or so of the taxes would be refunded.
I'll still try to find an alternative 318k eligible itinerary (so it would only be a 5k points change fee plus taxes) but it will be difficult.
However, if in the case that I was able to find another itinerary but only in PE instead of business, would I be refunded any points (assuming that my new trip falls under the PE cap of 249.6k points?).
Ie. I'd be refunded ~68k points minus any change fees if I was able to find an alternative OWA in PE rather than in Business?
Or, would it be better to just cancel completely, get my 318k points back minus the 6k points penalty for cancellation and just start fresh again?
Of course the option would be to not have to change, but it seems it's inevitable now / I wouldn't be able to find an equivalent Business itinerary at an alternative date.
Thankyou in advance!