Get 5,000 points for free when you add a supplementary card to your Amex card by telephone only for October 2016 November 11 2016 or around then.
I found out about this by accident when I phoned up Amex to dispute a transaction, and the girl told me about this offer. I'd already applied for a supp card on the website and the girl told me the points couldn't be applied, so I just applied for a new supp card!
You only get the points once, I asked about adding 3 supp cards and was told the promotion would only trigger once.
PHONE applications only!!
I don't think this is advertised anywhere and it's not targeted from what I can tell.
The phone number is 1300 132 639
Good luck :)
I tried to add a supplementary card on the website only last week and they wanted proof of identity documents, like the number of a drivers licence or passport. Your results may vary, but be prepared to have to provide this information as you may be required to.