how to change time zone to Perth time?

I have just bought a tivo and the guide has the shows 2 hrs in front of w.a time.How can i change this please so its back on perth time?

If you entered a 6XXX postcode then all the times should be correct.

Which shows are you talking about?

And just to confirm, it is a new TiVoHD you are talking about.

Peter.