我一直试图找出如何隐藏某些支付网关的基础上选定的航运。我一直在与此代码，但迄今为止没有。任何帮助？

add_action( 'woocommerce_after_checkout_form','woocommerce_custom_surcharge' );
function woocommerce_custom_surcharge() {
global $woocommerce;

 $chosen_methods = WC()->session->get( 'chosen_shipping_methods' );
 $chosen_shipping = $chosen_methods[0];

 if ($chosen_shipping == 'table_rate') {   

        function payment_gateway_disable_country( $available_gateways ) {

    unset(  $available_gateways['paytrail'] );

return $available_gateways;
}
add_filter( 'woocommerce_available_payment_gateways', 'payment_gateway_disable_country' );

}
}