if you are getting channel 7 from melbourne and not prime then you should be able to get it. there have been a few people saying they can get the EPG but the images on 72 are the same as 7, I wonder if you all have the same brand of set top box or something? my suggestions are to try and restore factory settings or use anything similar to that that your STB has the option for. also you could try unplugging it from the power point for a while, then plugging it back in and doing another rescan. if none of that works give the company that makes the STB a call and ask them what you should do.
Living in Geelong we get Melbourne's feed, but I can't get 7two at all.
I have a SD set-top box and after scanning, resetting and looking through all the 7 channels, still no 7two.
My father has an HD set-top box and after trying on his still nothing.
However, we can still access the EPG and look at the guide for 7two while the minimized screen (usually showing the channel browsing) shows 7.