Was just in Coles at Manly beach and same production date for Stage 3 as what your saw in Seven Hills - 03/04/2016 (photo below). The most recent date out of all of the brands.
Only 2 tins of stage 1, no stage 2 and about half stage 3 on shelf. It looks like BAL has ramped up production of stage 3 at the expense of stage 1/2 and now there are shortages of stage 1/2.