I received a call on my mobile phone from an Asian lady claiming to be from Mastercard, regarding a suspicious transaction made on my Mastercard. She told me they see a $600 plus transaction made in Tasmania today and they knew I am in NSW. She wanted me to quote numbers from my card to identify myself, which I did not give her. While on the phone, I checked my credit card account and saw no such transaction. She then said there was nothing more they could do but allow the transaction. I have not seen any unusual activity on my credit card.