I have a similar issue, I have adsl but no landline, while my house is inside a wireless nbn zone, nbn and telstra maps incorrectly show my house being 20km away from its real location. Telstra disconnected our landline because its connected to a part of the exchange that was supposed to be switched to connect to nbn, but sells us adsl because it thinks we are outside the nbn zone. When I tried to get our location corrected I was told the only way I could get the map corrected would be to purchase an nbn service from a nbn service provider and have them advocate on our behalf for a map correction. We had a visit from a telstra technician to test the landline (they had to be given directions on how to find us from 20km away when they followed their own incorrect map) an they said the line was fine and could not explain why they could not make or recieve calls, but we would continue to be billed for landline service as our line test result was good and they couldn't help us with map location error.