Hello,
1.
When the total cost is below 25€ for all products of the "Balloons" warehouse then the customer cannot complete the order.
If the order is over 25€, the shipping methods apply to specific areas (depending on the post code).
For example, if the customer lives in AREA A and the order's cost is 50€ then the process should be completed because we deliver in that area. If the customer lives in AREA B that's an area that we do not deliver so the order should not be able to complete. In that case we must display a message to inform the customer that we do not deliver in AREA B and to also hide the payment methods from the checkout.
Appart for the error message, were you able to configure it as you want ?
Also, If you want to display a specific error message in defined situations, the only solution will be to directly edit shipping methods related error translation messages. But it will only work if you want the error message to be displayed instead of the error message designed for that specific situation ("ORDER_TOTAL_TOO_LOW_FOR_SHIPPING_METHODS" for example).
2.
In the screenshot, the product belongs to the "Balloons" warehouse but the shipping address is not within the areas we deliver but in that case as a result i get the message "ORDER_TOTAL_TOO_LOW_FOR_SHIPPING_METHODS" and all the payment methods are displayed. That is not correct.
What do you mean by "all the payments methods are displayed" ? if that error message was triggered, you should'n be able to complete the checkout workflow.
3.
I'm sending you backend access to see for yourself!
Can you also give us the link to your website back-end space ? Thank you.
Kind regards,
Mohamed.