Firstly, I expect an ATO moderator from this Community will offer to assist you, offering a way for you to have a one-on-one conversation with someone who will take ownership of this situation through to its resolution. They're going to feel your pain too!
I also know the ATO has a robust complaints process, and I'd be triggering this in any case, @baker29 , given the difficulties you've endured. One of the steps is, of course, "Confirming your identity", so it might be interesting ...
After you lodge a complaint | Australian Taxation Office
And, given it's now been six months, @baker29 , and you find yourself involved in ongoing circular arguments with the ATO (we'll give you access to your account when you provide information from your account) it would not be unreasonable to skip the above step and instead directly approach the Tax Ombudsman.