Saw this on Big W home page - Get $20 Zip credit on shopping of $50 or more and using Zip payment method.
Expires 24-Sep. Couldn't find any more information on T&Cs. This is similar to credit at Chemist Warehouse, Pizza Hut etc.
(maybe just once per Zip account instead of 3 times like Pizza Hut). Will go nicely with the Toy sale.
Edit - New expiry date of 24 Sep (credit @xiangtan)
Edit - T&Cs now updated on BigW site - https://www.bigw.com.au/zip