public static decimal GetFinalPrice(Order order)
        {
            List <decimal> rebateprices = PromotionManager.GetActivePromotions()
                                          .Select(promo => PromotionManager.GetTotalRebatePrice(order, promo))
                                          .ToList();
            decimal origprice   = order.Products.Sum(x => x.UnitPrice);
            decimal rebateprice = rebateprices.Sum();

            return(origprice - rebateprice);
        }