The WDH lounge is not one of the SAA operated ones, so it would not surprise me if it is not a *G lounge, in which case you unfortunately dont have access to it on the strength of your *G car(d). Just check your facts before complaining to SAA.
Once you have done this, the email address of the WDH office is: [email protected]. See the SAA website under 'contact us' for more contact options (including 'phone and fax).