It seems losing that birthday card from your Nanna isn’t the only stuff up from Australia Post as they’ve just stuffed up their latest release of stamps.
Aus Post released a collectors edition AC/DC stamps, featuring Acca Dacca’s album covers. Nice sentiment except they’ve included the American album artwork, not the Aussie ones as pointed out by Noise11.com
Anyway, if you don't care about the stuff up you can get your AC/DC collector stamps here