While it's a taken a little while, Activision Australia have been kind enough today to inform of us of their plans for Australian (and New Zealand) replacement copies of Guitar Hero III: Legends of Rock for Wii. In case you missed it any Guitar Hero III Wii game bought since launch has been pressed incorrectly and all tracks have been made mono-only in sound no matter what the consoles settings are set to. To find out how you can have your Australian or New Zealand copy replaced head inside for more information..
Statement from Activision

We recently became aware that some consumers have not been able to enjoy the full audio output in the Wii version of Guitar Hero III: Legends of Rock. We are currently working with Nintendo and are planning to issue an improved audio experience in future versions of the game. We expect to have re-mastered discs available by early 2008 and we will be offering consumers replacement discs at no cost once they become available. Should you have any further inquiries, please contact Activision customer support at http://www.activision.com/support . Customers based in Australia wanting to pre-register for a free replacement disc can call (02) 9869 0955 (or 09 477 2582 for New Zealand) and we will notify you once the replacement discs are available. We thank all of our customers for their support and patience.

If you have a copy then there is no excuse not to get it replaced and play the game as the Rock Gods intended.