HI Richard,
We use VAST (3 boxes) whilst on the road so have quite a bit of experience with it. (also set the next 2 sats down from where i am camped).
If you are getting ABC and SBS it's nothing to do with the signal. Your Smartcard is "activated" as such but not approved for Free to Air. (7 etc)
ABC and SBS are approved when they register your card (everyone gets it) but you need to request access to all free to air as well.
Normally thats done by default, but i've had a few times when i've had to call and get them to redo it..
Also they will want the box setup and running on channel 800 when they do it. Normally it works even with not being online, but my older satking boxes didn't had to be activate.
You can also type in your smart card number here and try to do the activation yourself..
http://www.mysattv.com.au/decoderrehit.aspxThat worked recently for a guy a couple of camps down from me..