Your post has me puzzled, because I do not get any supplements, e.g. electricity, phone, rent assistance etc.
Every time I leave Australia, the supplement stops being paid after 6 weeks. When I return to Australia, it is restored in my next pension payment. That pattern has been followed for more than ten years.
I can only conclude you are getting the supplement as the result of some screwup, which is not unknown in bureaucracies.