If a neighbor’s tree is affecting your NSW, you can discuss the issue with them amicably and respectfully if they are not willing to cooperate, then you may need to contact your local council for assistance.
They will be able to advise on any laws or regulations that may apply in this situation and provide guidance on how best to proceed. You may also need to engage the services of a qualified arborist or tree surgeon to assess the tree and its effects on your property.