woocommerce/templates/emails/admin-failed-order.php

<?php
/**
 * Admin failed order email
 *
 * This template can be overridden by copying it to yourtheme/woocommerce/emails/admin-failed-order.php
 *
 * HOWEVER, on occasion WooCommerce will need to update template files and you
 * (the theme developer) will need to copy the new files to your theme to
 * maintain compatibility. We try to do this as little as possible, but it does
 * happen. When this occurs the version of the template file will be bumped and
 * the readme will list any important changes.
 *
 * @see 	    https://docs.woothemes.com/document/template-structure/
 * @author  WooThemes
 * @package WooCommerce/Templates/Emails
 * @version 2.5.0
 */

 if ( ! defined( 'ABSPATH' ) ) {
 	exit;
 }

 /**
  * @hooked WC_Emails::email_header() Output the email header
  */
 do_action( 'woocommerce_email_header', $email_heading, $email ); ?>

 <p><?php printf( __( 'Payment for order #%d from %s has failed. The order was as follows:', 'woocommerce' ), $order->get_order_number(), $order->get_formatted_billing_full_name() ); ?></p>

 <?php

 /**
  * @hooked WC_Emails::order_details() Shows the order details table.
  * @hooked WC_Emails::order_schema_markup() Adds Schema.org markup.
  * @since 2.5.0
  */
 do_action( 'woocommerce_email_order_details', $order, $sent_to_admin, $plain_text, $email );

 /**
  * @hooked WC_Emails::order_meta() Shows order meta data.
  */
 do_action( 'woocommerce_email_order_meta', $order, $sent_to_admin, $plain_text, $email );

 /**
  * @hooked WC_Emails::customer_details() Shows customer details
  * @hooked WC_Emails::email_address() Shows email address
  */
 do_action( 'woocommerce_email_customer_details', $order, $sent_to_admin, $plain_text, $email );

 /**
  * @hooked WC_Emails::email_footer() Output the email footer
  */
 do_action( 'woocommerce_email_footer', $email );