Welcome to the community!
We would love to help and see what happened on your service installation. There is a possibility that the equipment for NBN service that was installed in the premises is only available for 1 user. We tried to use your Community details to pull up the account unfortunately it does not show any matching records on file.
To better understand the situation, we would like to get your account details (Username/Customer ID together with the complete address).
In case you need a reference:
Hi Rebecca, just found your post on this forum (after 6 attempts to register) and was hoping you had a successful outcome? Could you let me know as I am experiencing something similar - although our new build is not a duplex (doesn't share a party wall) and has been given a different street address by the local Council.