I did call my Mastercard provider (not the number that I was told to ring, but the number on the website). This mobile ph number is their automated alert phone number. The automated ph call made to my mobile ph was their Fraud Detection Unit. More relieved now, since they have confirmed that the 0458 202 202 & 1300 627 831 numbers are their numbers. Legitimate.

Claiming to be NAB master card fraud. Automated respose service. Disconected when called. Unsure of its legitimacy.