robocall telling me I have just successfully purchased a $390 item from ebay

Telstra scam, I knew it was a scam as soon as he said it was "Peter from Telstra"... beware, they tell you that they want to help you with your internet speed, then when I told him that there was nothing wrong with my internet speed, he told me he was there to help me, clearly reading from a script... I wanted to stay on for as long as I could to get more details of the scam but got fed up when he asked me to check the "colours of the lights on my 'rooter'" - ridiculous... I hung up then.

Caller: Indian Scammer

Claimed to be from Amazon prime telling me I hadn't paid my bill. I decided to have a bit of fun and see if this nong knew anything about Amazon. I played along and then asked, "I need to get you to prove to me that you are calling from Amazon. Can you tell me the name of the Founder, the city where Amazon HQ is located and the name of the founder's spaceship?" The moron insisted that Amazon's CEO is Scott Morrison!

Missed call yesterday. I didn't call back.
I'd had a couple of texts "from Telstra" that I'd ignored and deleted as there was no reason Telstra would be contacting me.

Another scammer - supposedly from Telstra threatening phone disconnection

Caller: claimed to be NBN security :-)

Watch out people.
First red flag - An automated voice will be telling you your NBN connection will get interrupted due to some issues and to press 1 to get redirected to a technician.
If you don't do it, you get redirected to an an actual person.
Second red flag - that person has a heavy Indian accent and claims to be a NBN security person and there has been happening some suspicious activity on your network.
I let him finish his BS story and asked him what provider I am on as he should know if he is from the security department. The guy immediately hanged up.