Hung up when answered. Cannot call number back

I received a call from this number, it was a recorded message saying this is Telstra and that my phone would cease to function in two hours. Not long after I received another call this was a NEW ZEALAND number which I returned the called from another phone. I spoke to the lady and gave her the number of the call. She was adamant she did not call me. Not long after that call I received another call. This time the number was (02) 8552 5247. I looked this number up via Reverseaustralia, NO SUCH NUMBER FOUND. And another call, (02) 8552 6348 and (02) 8552 6386. All SCAM NUMBERS.