Actually, we do have a Telstra business rep, and I have spoken to her twice now with no result either. Very disappointing.
But on to a more positive note - Another HN user who actually works for Telstra saw my post above and reached out to me via email to try and reach a resolution. I really appreciate that he did this on (a) a public holiday and (b) took some effort to find me email address to reach out to me on.
Fingers crossed that he can sort things out where others have not been able to.