function process_payment( $order_id ) {
global $woocommerce;
$order = new WC_Order( $order_id );
// Mark as on-hold (we're awaiting the cheque)
$order->update_status('on-hold', __( 'Awaiting cheque payment', 'woocommerce' ));
// Remove cart
$woocommerce->cart->empty_cart();
// Return thankyou redirect
return array(
'result' => 'success',
'redirect' => $this->get_return_url( $order )
);
}