Is your order stated to arrive on Sept 1st?
If so, take my advice: contact support via chat another time.
This happened to me once too, but what the support staff member told me was simply not true. He even sent me out a mail explaining the "out of stock" thing, suggesting me to delete my purchase. Than I contacted the support again and the staff this time helped me, telling me my order was ok and, since I was able to pre-order it, I would receive it in time.
And I received it in time.
If your order status is ok, you'll probably receive the order as planned.