Currently Telstra are offering a 30GB, $49 postpaid plan discounted to $39. To be eligible you have to have an existing service and be adding a new service. If you want to signup an existing mobile which is out of contract, the discount is not available. You could cancel the current plan and sign-up to get the discount but you get a new number.
This seem to be actively discriminating against existing customers. Isn't there some discretion to incent existing customers to re-contract for 12mths?
I can appreciate your concerns with the discount not being available to existing customers and apologise for any inconvenience this has caused I will be happy to pass your feedback on through to the Products team for consideration on future plan releases.
I hope that we do have something available that would be more suited to your needs in the near future.