Hi
Tonyed, what state are you in? It may depend where you are located as to the specific requirements for a boundary survey notice, however I know that in Victoria and some other states there is no prescribed notice, so you can just write a letter giving notice to your neighbour setting out your intention to have the common boundary defined by a licensed surveyor unless the two of you can agree on its location. Make sure you date it and keep a copy of it for yourself.