Burswood I believe you. A mess indeed.
I can't ever remember an example of either ex Div Date or record date being stated as pre announcement date. Whether this is legal or not I don't know but I can see this would be be a problem for GNS.Also a drag in the price.
As you probably know the Ex Div date is not released on the announcement date so they could still come up with the Ex Date post announcement. I'm sending them a query today.