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 ;
        }
    }