Debra, I am in the exact same position and I can assure you, unless you have 3 years worth of documented evidence and affidavit of sworn witnesses, there is nothing you can do retrospectively: in fact, nothing substantial you can do legally even in the present.
The first and immutable step is to initiate mediation.
Neither police nor legal people will take any notice of you unless you have taken that first step - particularly if they decide there is no 'criminal' act in the harassment. They will immediately begin referring to it as 'just' a 'neighbourhood dispute' at which point you will be totally patronised and then ignored. 'mediation' is the catchword for all social, legal, justice and law enforcement personnel. If you believe your neighbour will not stop harassing you in the interim, start keeping a diary of those harassments immediately.
If your neighbour rejects mediation there is still nothing you can do without evidence. Police and legal personnel will ask to see your proof of his/her tailgating. Proof of his/her verbal abuses. This means you have to have audio & visual CCTV proof, and/or impartial witnesses willing to sign affidavits - and most people [70% of Australians in fact] 'don't want to get involved'; and the behaviour you describe will not be viewed as criminal and therefore not worth the attention of our mighty police force. And the more you complain and ask for their help, the more they will view you as the cause of that 'neighbourhood dispute'.
It is true we are all entitled to quiet enjoyment of our land, but you have to offer substantial and consistent proof that you are being denied that proof. House ownership/rental is of no consequence as we are all equal before the law. A solicitor at this point will only be able to write and ask the person to cease and desist in an officious manner. This may scare your neighbour into compliance. on the other hand, it may incite an escalation. Not worth the money the solicitor will ask for such an action I don't think...
If you haven't done so already, you could write to your neighbour explaining how you feel and asking her to stop...Invite her in for coffee and a talk about the situation, etc...[keep a copy of all documents!].
Basically, that is an attempt at mediation too, but unless you go through the 'official' channels, it won't count.
Bullying is not illegal in Qld - only Victoria. If it wasn't so damn cold down there I'd move just for the safety of that legislation! Up here, the system still requires physical injuries and/or a corpse before acting. No doubt you will understand after three years as well, why i am so frustrated.
Hope this experiential information helps you