Issues with DCB in Australia, page-7

From Telstra's how to manage your content site:

If you don't want it just bar it on your account. Problem solved.

"You can bar all future subscriptions on Premium SMS services or Telstra Carrier Billing on your mobile free of charge. Once barring is activated you can't receive, be charged for or use 19 numbers or access any app stores or media portals."

Or Telstra also allows to set a spent limit:

"The standard spend limit for Premium SMS and Telstra Carrier Billing is $100 per month for Post-Paid customers"

More info here:
https://www.telstra.com.au/mobile-phones/moreonyourmobile/manageyourcontent