Update Xml Element Using C#

           var xdoc = new XmlDocument();
            xdoc.Load(webConfigPath);
            var endpointNodes = xdoc.SelectSingleNode("/configuration/system.serviceModel/client /endpoint");
            if (endpointNodes != null)
                endpointNodes.Attributes["address"].Value = addressValue;

            xdoc.Save(webConfigPath);