This Black Friday deal is back again for Christmas. They are offering $10 off their Mx plan (10GB data per month). This is a 12 month contract, minimum cost is $468, unlimited national talk and text. All support must be handled online (hence the 'x' in the plan title).
For new customers, and exisiting Telstra customers have to port over to a new number. As I've seen in the Black Friday deal, you can get 5GB extra data on top of the 10GB with some negotiation through webchat.
EDIT: Try using different browser/device if it doesn't show up straight away.
I'm currently on 12GB for $40 with Telstra. Got it through live chat.