There's a lot of extra chances to boost your Coles Gift Card in their "Giant Gift Card Giveaway" by presenting vouchers for certain cleaning products. From Coles' email just now (edited slightly :) :
It's official, the spring cleaning season is here! As a Giant Gift Card Giveaway customer, we've got lots of fantastic BOOST offers on a wide range of cleaning essentials, exclusively for you.
You could earn up to $15.00 extra on your Coles Gift Card by redeeming the vouchers on the promotional products in-store.
Get the PDF uploaded and print your Spring Clean Boost Vouchers valid throughout September. Present them at the checkout with your FlyBuys card at the time of purchase to boost the value of your Coles Gift Card even further. It's that easy!
There's terms and conditions on each of the vouchers in the PDF. They look the same, but check each one for details. Here's the first as an example:
Voucher Conditions: Offer only valid for customers who are registered for the Coles Giant Gift Card Giveaway. FlyBuys card must be presented at the check out with a valid Voucher at the time of purchasing the qualifying product. This Voucher is valid for one transaction only at Coles Supermarkets, Coles Central, Bi-Lo and Pick ‘n Pay between 03/09/09 until 30/09/09 and must be surrendered at point of purchase. Vouchers that have been altered or passed expiry date are not valid. Not valid at Coles Express or Coles Online. Not to be used in conjunction with any other offer. Valid whilst stocks last. No Rainchecks. You can only qualify once for this promotion.
I wonder if the original vouchers required???