Hello,
I need to set up different postage costs and tax rates for professional customers. Shopify's default customization options don't allow for this, so I've decided to create a Checkout UI extension. Figuring out how to do this for professional users is straightforward, so let's skip that.
The challenge lies in changing the postage cost and tax rate before making a payment. I need help finding an option to create a mutation for this. The only way I've found to change something in the shipping is to change the shipping address. I've considered using the Shipping Discount Function API, but there's a problem when the shipping cost needs to be higher, not lower.
Do you have any advice or workarounds for this issue?
