Missed call, called back; voice stated ' the number you called is not connected'??

Computerised call, threatening to disconnect home internet and phone within 24 hours if I didn't sign up to an NBN plan immediately

Caller: 0490 957 618

Said they were from NAB bank and my account was compromised.. More callers in the background.

They hung up when I answered

Caller: Said it was an nbn update

Rang my aunt, she got them to ring me, told them to email what they were offering, got heated, when I kept asking who he was with, then told me the address he was calling, and I told him anyone can access an address via white pages. He eventually hung up

Said they were Centrelink asking if I'm a pensioner, said Centrelink do not use mobiles where are you really from. Kept asking if I was a pensioner then spoke to someone in background then hang up. Who are these people - scammers. How can we stop them?

computerised call scam saying antivirus has expired. call a number(couldnt get the number as spoke too fast) to stop renewal.