Getting a new or replacement dividing fence can be a challenge, especially if your neighbour doesn't agree with your choice in fence. It helps to discuss the details with your neighbour upfront, and if that doesn't work you need to know your rights.
The act that refers to dividing fences (that is fences that divide two properties, not retaining walls) is the 1991 dividing fences act. You can see this act at http://www.lands.nsw.gov.au/crown_land/dividing_fences .
Also below is a downloadable document that outlines some things you and your neighbour should discuss as well as where to get your permit forms and links to other useful websites.
North Coast NSW - T: 6591 3521
Central NSW - T: 6764 5113
Southern NSW - East - T: 4428 9100 West - T: 6993 1306
Hunter/ central coast region - T: 4937 9349
Sydney region - T: 8836 5332
Far West NSW - T: 6883 3004