Tarbs actually doesnt exist in Australia they went broke and are now operating as UBI( same people different name).
The are transmitting on Optus B3(check
www.lyngsat.com for more details) altough I,m not sure if you will be able to see the satellite from Western Australia??
You will need a Old Tarbs satellite Box and smartcard if you can get your hands on one and then call UBI in Sydney to see if they can activate the card for you