We don't generally purchase shipping labels in Shopify for INTL orders. This is done on a separate application connected to Shopify. 

However, if there is ever a reason to do this in Shopify, please follow these instructions:

To correct shipping costs for international orders, you'll need to edit the order directly:

1. Go to Orders in your Shopify admin.
2. Click the order you want to edit.
3. Click Edit.
4. In the Payment section, click Edit shipping fees.
5. Click the trash can icon next to the shipping rate to remove it.
6. Click Remove.
7. Add the correct shipping rate and update the order.