hi Cam, your postcode must be set up wrong in your account if it is that far from where you live.
In the shipping profile select "I will enter the location" and enter in the box what you want to show instead of your postcode.
You may need to select this shipping profile into the required master profile again to update it, long time since I have updated mine.
I would also expect that this change only applies to new listings created with these profiles and it will not be automatically applied to existing saved or live ones.
To change existing saved listings the 'find and replace' option in the saved listing folder should do the trick to replace the 'shipping field', however when I tried to update some recently due to a change in shipping costs it would not update the shipping fields although it said it had.
Best try on a few then visibly check them before posting to ebay.