Cannot set up mobile connection between apple watch 6 and iphone 11pro with Telstra

Hi all,

I'm frustrated beyond belief, I've had my watch now for 20 days and have not been able to establish the One Number connection with Telstra. Everything is working perfectly on the watch, it pairs with my phone etc, but every time i go to do the mobile connection it tells me 'Opps, something went wrong" on a telstra screen

I have a fault registered with them in the system, and have been through so many computations of resetting everything including the last of doing factory resets on both my phone and watch, but still cant get a connection. They keep telling me that there is no fault at their end, and it is something to do with my devices.

Has anyone else come up with something like this??

I don't know what to do next

thanks