Caller: Call from "Telstra NBN"

Told me to log into team viewer on my computer so they could access my computer to switch over to NBN. Threatened that I would lose all internet and phone connection immediately if I didn't comply. Sounded sus but almost had me fooled as NBN has just been installed in my street. Gave me another fake "Telstra" number to call when I questioned their credibility 1800 431 346