Work with shipping zones and shipping calculation plugin

Hi

I seem to have a shipping calculation plugin that ignores everything I have set up in my Shipping Zones. So I am looking for a way to achieve the following very simple setup:

– Free shipping for all orders over $99 if the buyer’s postcode (within Australia) falls within certain ranges (i.e. metro). For all else, let my AusPost shipping plugin calculate it as per usual.

Sounds imple enough, but can’t find a solution.

So I have set up the following shipping zones:

* A zone with postcode ranges (metro postcodes – this is a big long list of individual postcodes and also postcode ranges eg. 4573…4599, etc), with a Free Shipping method enabled with minimum spend set to $99 (which I can remove if your plugin requires); and
* A zone to capture all other postcodes (i.e. the rest of Australia), with no free shipping module or any other method enabled.
* Additionally, I have disabled the free shipping minimum spend amount in my AusPost plugin, as it looks like that is a global setting that will override everything regardless of shipping zone.

As it is (ie. without the help of your plugin), this is currently not working, hence I’m trying to find another solution. Is there a way to define rules by shipping zone in your plugin? If not, what format should your postcode ranges be in? Will your plugin allow everything outside of its rules to be calculated by the normal site method (ie. my AusPost calculation plugin)?

Apologies for the long question – would love to know if your plugin can help with this. Very much appreciated.