Just received this note on my latest statement, 4 April is when the amex card will end.
Important notice - Your Singapore Airlines Westpac Platinum American Express® Card will close on 4 April 2018 Regulations introduced by the Reserve Bank of Australia earlier this year, affect credit cards issued by Australian banks, particularly bank-issued American Express Cards. In response, we have reviewed our reward credit cards and want to notify you that from we are closing all Westpac-issued American Express Cards. If your American Express Card expires in March 2018, you will not be reissued with a new card, and your card will close earlier on 31 March 2018. You will no longer be able to use your Singapore Airlines Westpac Platinum American Express Card from the date of closure. If you've set up any automatic payments on your American Express Card, you'll need to contact the merchant directly before your card closes and provide alternative credit card details. We apologise for any inconvenience this may cause. You can continue to use your Singapore Airlines Westpac Platinum American Express Card to earn more points until it closes.
These changes do not affect your Singapore Airlines Westpac Platinum Visa Card and you can continue to use your card as you do today. "