Function to have WooCommerce send an automatic support email to the customer for orders that switch to a status of cancelled.

woocommerce-support-email.php

<?php
add_action('woocommerce_order_status_changed', 'send_support_email');

function send_support_email($order_id) {
	$order_data = new WC_Order($order_id);
	global $woocommerce;
	$mailer = $woocommerce->mailer();
	if ($order_data->status=='cancelled') {
	
		$to =  $order_data->billing_first_name . ' <' . $order_data->billing_email . '>';
		$subject = 'Trouble with order #' . $order_id;
		$message = $mailer->wrap_message('Trouble with order #' . $order_id, 'We noticed that your recent order was cancelled. As a courtesy we wanted to make sure that you did not need any assistance. If you do please contact us by replying to this email. Otherwise you do not need to do anything.');
		
		woocommerce_mail( $to, $subject, $message, $headers = "Content-Type: text/html\r\n", $attachments = "" );
	}
}