Best Extension For Shipping with overlapping postcodes

Hi – I am building a site where the user can buy, in its simplest form, 2 products. Product 1 has a small shipping fee and can be sent to all of NZ. Product 2 has differing shipping fees based on the postcode and only sent to a certain area of NZ. I was able to successfully set up the 2nd product by postcode but when I added a shipping rule for the 1 product, it worked fine for a postcode not associated with the Product 2 shipping rules but when using a postcode as assigned to Product 2, when it came to checkout, Woocommerce chooses the most expensive cost depending. Is there an extension where I can use per product shipping. I purchased the INNOZILLA PER PRODUCT SHIPPING PRO but my WP just freezes.

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