I had been waiting on a bundle I ordered online (iphone 8 64gb) and iwatch 38mm and had noticed my status was 'confirmed' but had not received any further updates via email or telephone.
My partner then informed me that the 64gb iphone 8 was now listed as 'out of stock' on the optus website so I became a bit concerned and contacted a representative via online chat (I remember his name but I won't publish it here for privacy reasons).
I asked him about the status of my order and he said he'd look into it for me. He then informed me that yes, the iphone which I had placed an order for was indeed out of stock due to a supplier 'not meeting their expectations'. I then notified him that I'd received no communication from Optus on this issue and asked for an approximation in terms of when my requested item would likely be in stock. He was unable to give me an answer.
At the end of the conversation, I requested a copy of the transcript be sent to my inbox.
Previously with another representative, this had not been an issue and a transcript was received promptly.
On this particular occasion, I've checked all my inboxes (including my junkmail) and have received nothing.
For a new optus customer, I am really disappointed with the level of service that I've received and am starting to regret having signed up at all.
If Optus can't provide a reasonable stock availability then you should be free to cancel the order (if that's what you want to do).
IME Apple and Optus have some behind the scene issues. That's in addition to the general stock issues Apple has had at times with its newer models. You're possibly better off buying a unit direct from Apple if you can afford the upfront cost (walk into their store and they'll give you one on the spot).
Couple that with a much cheaper Optus SIM only plan and you'll likely save (or break even) on the TCO over the life of the plan. you'll need to do the sums though.