......
<wsu:Created>2013-02-05T08:20:10Z</wsu:Created>
<wsu:Expires>2013-02-06T08:30:20Z</wsu:Expires>
</wsu:Timestamp>
<wsse:UsernameToken >
<wsse:Username>Username</wsse:Username>
<wsse:Password>Password</wsse:Password>
.......

using System.Configuration;

......

System.Configuration.Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None); 

                BindingElementCollection elements = client.Endpoint.Binding.CreateBindingElements();
                elements.Find<SecurityBindingElement>().IncludeTimestamp = false;
                client.Endpoint.Binding = new CustomBinding(elements);