var  ChannelFactory<Overview.MyChannel> cf;
        var relayNamespace ="myrelaynamespace";
        var relayListener = "myrelaylistener";
        var endPointAddress = new EndpointAddress(ServiceBusEnvironment.CreateServiceUri("https", relayNamespace, relayListener));
        cf = new ChannelFactory<Overview.ItServiceManagementAOChannel>(binding, endPointAddress);
        ClientCredentials loginCredentials = new ClientCredentials();
        loginCredentials.UserName.UserName = "onpremWCFusername";
        loginCredentials.UserName.Password = "onpremWCFpassword";

        cf.Endpoint.Behaviors.Add(new TransportClientEndpointBehavior
        {
            TokenProvider = TokenProvider.CreateSharedAccessSignatureTokenProvider(ConfigurationManager.AppSettings.Get("WcfRelayKeyName"), ConfigurationManager.AppSettings.Get("WcfRelayKey"))
        });
        cf.Endpoint.Behaviors.Add(loginCredentials);

using (var ch = cf.CreateChannel())
        {
           try
            {
               var resp = ch.CreateTaskAsync(req).Result;
            }
         }

factory.Credentials.Windows.ClientCredential.UserName = "administrator";
factory.Credentials.Windows.ClientCredential.Password = "123456";
IService sv = factory.CreateChannel();