Caller: Someone purporting to work for an electricity retailer

Called me on my brand new (less than 3 week old) mobile phone number on a new phone that hasn't been used/connected to ANY online accounts, nor has my number been given to anyone yet.

Somehow though, they already knew my nickname and were NOT asking for me by my full name (registered to the phone number).

Data harvesting, aggregation and the selling there of, is REALLY starting to P me off.

I called back number (03) 9448 9964 reached voice mail but did not say for what company.