Sent a text message saying "Dear Customer Your ATM Card has been Block because you have not update if you want to keep use your ATM card please call our number (02) 8003 3204". I tried to call it to find out what the scam is but it rang out each time.

this number is a scam. there is no identity of who they are calling from and no financial institution would get you to verify your card this way.

Please be careful if you get am SMS from this number and do not reply to their message.