public string FetchToken(string SessionID)
    {
        string callname = "FetchToken";

        #region Initialise Needed Variables

        //Get the Server to use (Sandbox or Production)
        string serverUrl = ConfigurationManager.AppSettings["TradingService"];

        //SiteID = 0  (US) - UK = 3, Canada = 2, Australia = 15, ....
        //string siteID = "0";

        eBayAPIInterfaceService service = new eBayAPIInterfaceService();
        string requestURL = serverUrl + "?callname=" + callname + "&siteid=" + siteID
                            + "&appid=" + AppID + "&version=" + version + "&routing=default";
        service.Url = requestURL;

        // Set credentials
        service.RequesterCredentials = new CustomSecurityHeaderType();
        service.RequesterCredentials.Credentials = new UserIdPasswordType();
        service.RequesterCredentials.Credentials.AppId = AppID;
        service.RequesterCredentials.Credentials.DevId = DevID;
        service.RequesterCredentials.Credentials.AuthCert = CertID;
        #endregion

        FetchTokenRequestType request = new FetchTokenRequestType();
        request.SessionID = SessionID;
        request.Version = version;
        FetchTokenResponseType response = service.FetchToken(request);
        return response.eBayAuthToken;
    }