Caller: "Norton 360"

Email received from messaging-service @ post.xero.com with the subject: Invoice from Norton 360 for <my email address>.

The email asks to "Kindly call support (03) 6163 3333"

It's just a scam number, albeit very well dressed scam. Hope they don't catch anyone!

Caller: an email from "norton av" using a xero from-address

Why aren't the telco's chasing the owner of this valid victorian phone number which perhaps has been hijacked or redirects overseas or whatever.

Caller: Number received in scam email asking victim to "please call"

This number is included in a scam email from messaging-service @ post.xero.com asking the victim to call this number to arrange payment. These have been turning up with fake invoices for such things as Norton or Microsoft products.

Interestingly all of the email headers match a legitimate Xero sender so I suspect the scammers are using a stolen Xero account to send these out through Xero's own messaging service.

email from messaging-service @ post.xero.com
asking for Norton subscription renewal with call to cancel.

This is an absolute scammer. Avoid at all times. They say they represent Microsoft and will attempt to con you in opening an app to access your iPhone or computer.
Received email advising that $349.99 annual Norton subscription was to be renewed and they had taken money from account. To cancel subscription you will need to call this phone Number.