Nice find from OzBargain user amy12345 Full credit to them for this post.
Not sure if anyone's posted this but I discovered a bit of a hack. If you add something to your cart on the app (literally anything), it then gives you the option to add on extras, one being 2 hot and crispy for $2.95. You can then add as many of the 2 for $2.95 as you want. It ends up costing a little more but at least you can still get it.
Given that KFC were selling too many of the 10 for $10 deal this is the next best thing. It's believed they had to end it early so stores had enough stock to put in their advertised $4.95 fill up box and the Boneless Hot & Crispy box.