using System;

using System.Xml;

using System.Xml.Linq;

using System.Linq;

public class Program

{

    public static void Main()

    {

        //string XML = @"<Token xmlns=""http://payments.exigo.com"" xmlns:i=""http://www.w3.org/2001/XMLSchema-instance""><CreditCardToken>37E1CQR834N72069</CreditCardToken></Token>";

        string XML = @"<Fault

                      xmlns=""http://schemas.microsoft.com/ws/2005/05/envelope/none"">

                      <Code>

                        <Value>Sender</Value>

                      </Code>

                      <Reason>

                        <Text xml:lang=""en-US"">Invalid Credit Card Number length</Text>

                      </Reason>

                    </Fault>";

​

        XDocument xdoc = XDocument.Parse(XML);

​

        //Valid Response -- Error

        XNamespace ns = "http://payments.exigo.com";

        XNamespace nsa = "http://schemas.microsoft.com/ws/2005/05/envelope/none";

        var element = xdoc.Elements(ns + "Token").Elements(ns + "CreditCardToken")

            .FirstOrDefault();  

        var error = xdoc.Elements(nsa + "Fault").Elements(nsa + "Reason")

            .FirstOrDefault();

        // Check if Valid Token Response

        var anything = xdoc.Descendants(ns + "Token").Any();    

        // Check if Error response

        var error_exists = xdoc.Descendants(nsa + "Fault").Any();

​

        if(anything){

            Console.WriteLine(element.Value);   

        }else if (error_exists) {

            Console.WriteLine(error.Value);

            Console.WriteLine(error_exists);

        }else {

        }

    }

}