I'm sorry to hear that! This error looks like it is coming from the customer's side, so the customer will need to check with their bank to see why their card was declined. The error code 'do not honor' lets us know that the customer's bank has advised not to charge this card:
I can break the process down a little for some clarity.
Unfortunately, there can be many reasons why a charge is not accepted, so the error messages we receive back are not very descriptive. And as the sale did not go through because of an error on the customer's end, there is not a lot we can do here. Would you have any other payment methods available apart from Shopify Payments? If you were to use something like PayPal, the customer could try to pay this way instead! Though if the same credit card is attached to their PayPal account, they will most likely see the same error.
You could offer to investigate the issue for them if you like, the abandoned cart recovery email will automatically reach out to the customer after the sale has not been completed.
Let me know what you think!
Social Care | help.shopify.com