Add a 'Change payment' button to the Subscriptions page in the My Account area

wcs_add_change_payment_button_to_subscriptions_page.php

<?php

function wcs_add_change_payment_button_to_subscriptions_page($subscription) {
    $actions = wcs_get_all_user_actions_for_subscription( $subscription, get_current_user_id() );
    if(!empty($actions)){
        foreach ( $actions as $key => $action ){
            if(strtolower($action['name']) == "change payment"){
                $changePaymentLink = esc_url( $action['url'] );
                echo "<a href='$changePaymentLink' class='button change_payment_method'>".$action['name']."</a>";
            }
        }
    }
}
add_action( 'woocommerce_my_subscriptions_actions', 'wcs_add_change_payment_button_to_subscriptions_page', 10 );