Win Free Stuff is a site offering a list of current Australian competitions. If you join the site you can subscribe to the newsletter, or you can visit the site as often as you like to see the current competitions. The competitions are grouped by state, type, prize & sources. 386 competitions are listed as of today.
The site doesn't appear to have a phone or an address listed.
One word of warning though, as with any competition you are swamped with emails, so it's a good idea to create another email account to deal with the influx.