They still have not put up Sept tickets for Last Supper. The website seems to say they should be available. But they aren't, even on the third party sites. Is there some closure or glitch?
They opened up at 12:01 a.m. on July 24 and sold out pretty quickly. When you go to the "buy" page on vivaticket you have to "right arrow" through the calendar to get to September's page. August has been showing availability on the week-ends today (as many as 14 tickets in some time slots), so maybe September will do the same at the end of August. That's my hope anyway since I didn't manage to get any in the early hours of the 24th.
Did you call the number 02 9280 0360? I was told there is availability when you call even when there is no availability on the website.
See this other current discussion about Last Supper tickets as it might be helpful: