Welcome to the community!
At the moment TPG do not have a feature to block a certain number. But you may consider reporting the numbers to ACMA via this link: http://donotcall.gov.au. If you have a handset that has an option to block in coming call you may also use it.
Let us know should you require further assistance.
The Do Not Call Register is ineffective.
Our telephone is registered with them (for many years) and we still get between 10-15 nuisance calls per day.
I would encourage TPG to think again about adding call blocking to their landline service or recommend suitable handsets that have this function.
(a) it would make TPG landlines very popular, and this would be a good selling point to distinguish TPG from the crowd.
(b) it would encourage people to use their landlines which in turn would generate income for TPG.
At the moment all incoming calls on our landline are scams and telemarketers (the only exception is a pre-arranged time on Sunday for my parents to call). Not being able to block these scam calls has meant we no longer using our landline for any outgoing calls = no call income for TPG. I also unplug the handset when I'm working at home to stop the ringing.