public string GetOrderUpdateRequest(int orderID, bool invoiced)
        {
            XDocument x = new System.Xml.Linq.XDocument(
               new XDeclaration("1.0", "utf-8", "yes"),
               new XProcessingInstruction("webcretexml", "version=\"1.0\""),
               new XElement("WebcreteXML",
                   new XElement("WebcreteXMLMsgsRq",
                       new XElement("OrderUpdateRq",
                            new XElement("OrderUpdate",
                                new XElement("ID", orderID),
                                new XElement("Invoiced", invoiced))))));

            return x.ToString();
        }