I'm having an issue with the discount coupons contribution and have been unable to find an answer to it here.
It occurs when using the table rate shipping method based on order total. If someones order total is just over one of the thresholds in the shipping table and they enter a discount coupon that takes their order total below that threshold they are presented with an error message that says:
'Your calculated shipping charges have changed'
They are then taken back to the beginning of the checkout process, but are unable to checkout as this happens each time.
Can the coupons be configured to apply a discount to the order total including shipping so that this isn't a problem? Is there another fix?