You must inform Westpac card centre that you are going overseas and where as they watch your card while you are away, this is a must do with Westpac.
Daughter had to do this with Westpac before she left for Eroupe, the states then for Bali. These were 3 seprate trips, they wanted to know dates etc. If they see your card being used in foriegn country and you haven't informed them, then they will cancel the card. Westpac card services will ask you for a mobile number while you are away.
Before cancelling your card they will try and contact you first but if they can't get a hold of you then they may cancel it, if you haven't informed them first.
In actual fact most banks want this information prior to people going overseas because of the high rate of fruad.
I thought you should know this before you go.