She tried to make a purchase, but the website said that her pin was invalid.
However, when she looked at her bank statement, the transaction is pending on her statement (she sent me a screenshot).
What do I do?
I recommend you to email directly to Shopify's Merchant support.
Contact page link: https://help.shopify.com/en/questions#/contact/email
Thank you for your message, I would be happy to offer you some suggestions for this. First, have you checked your Abandoned checkouts section to see if the failed order showed up there? You can do so under Orders>Abanadoned checkouts in your admin like this:
if it did, it should show you the specific reason the order did not go through. With many banking institutes even if your card fails when making a purchase, it will show as pending or failed on your banking statement. Your customer will need to reach out to their banking provider to look into this further.
Feel free to reach out to us directly with any questions you may have, we are always happy to chat.