If you did not feel like installing an App for getting 1 free coffee, how about 9 coffees for $13? (https://www.ozbargain.com.au/node/233164)
I found that you can use all the coupon codes in the Skip app. So you can get,
1 Coffee - IEATMELBOURNE - Free Expired
3 Coffees - 3@$1 - $1 each
5 Coffees - 5@$2 - $2 each
You can also get 4 Coffees at 1/2 price with these codes:
1 Coffee - 1@1/2
3 Coffees - 3@1/2
Use one code at a time and when you exhaust the limit of the code, use the next code. I think using the code in the above order will be optimum.
NOTE: Even if you have used the free coffee code from the earlier deal, you can still use the other codes.
You can find all the coupon codes here: http://skip.com.au/terms/skip-promo-terms.html
Wow i think i might die from caffein overdose today so ill give u an upvote now