Sounds like a pretty good deal!
Deal extended from 31 October 2016 to 31 January 2017.
Apply for a new Low Rate or Low Rate Gold credit card before 31 January 2017 and if you spend $500 by 31 March 2017 we'll give you $250 cash back. Plus, we'll waive the annual fee for the first year. Conditions apply*
Don't think it will work. Most likely you'll have to refund onto the same card.
What is Bunnings return timeframe?