WCF Could not establish trust relationship for the SSL/TLS secure channel with authority

A custom remote certificate validation can be used to avoid the strict validation, instead, just make it trust anything.

In your code, simply make a call to the static method SetCertificatePolicy() once within your application before making any request to the web services.

// note this code is not intended to used 
    // in production enviroment
    public static class Util
    {
        /// <summary>
        /// Sets the cert policy.
        /// </summary>
        public static void SetCertificatePolicy()
        {
            ServicePointManager.ServerCertificateValidationCallback += RemoteCertificateValidate;
        }

        /// <summary>
        /// Remotes the certificate validate.
        /// </summary>
        private static bool RemoteCertificateValidate(
           object sender, X509Certificate cert,
            X509Chain chain, SslPolicyErrors error)
        {
            // trust any certificate!!!
            System.Console.WriteLine("Warning, trust any certificate");
            return true;
        }
    }