Hello, my name is ***** ***** I am a qualified lawyer happy to help you today.
Assuming your neighbour will not talk to you then the next step would either be a letter from a solicitor or a cease and desist letter from you (as a prelude to applying for an injunction to the local county court). A strongly-worded letter from a lawyer would be a good idea and shouldn't cost too much. You can check your local area for law firms who deal with property disputes and ask if they could help with one letter to the neighbour. The other option is to send the neighbour a warning letter (to give them a chance to avoid litigation).
Before applying for an injunction then you or your solicitor needs to send the neighbour a cease and desist letter to warn them of your intentions unless they stop (and give them 7 days to stop their conduct). A template “cease and desist” letter is available at www.lawdepot.com
Assuming they continue, you will need to complete the attached claim form N208 and N16a and send to your county court with a fee of £308 payable to HMCTS (unless you have a low income/low savings and/or you are in receipt of benefits in which case you can get a fee exemption so you do not have to pay). For a fee exemption you need to also send to the court form EX160 (also attached). If you do not qualify for the fee exemption, you can pay either by cheque or attend the court and pay at the counter. You will need to prepare a witness statement to accompany the form. A template is attached for you to use.
You will need to detail the history of the issues with the neighbour, what was said, the arguments, and so forth - to paint a picture for the Judge as they will not know what this neighbour is like unless you describe it.
If the injunction application is successful you can ask for repayment of the fee from the defendant.
The court will list a hearing where you attend and ask the District Judge for an order and the injunction.
If granted, the Order is then served on the individual concerned and they are bound by the court order - if they breach the order, they are in contempt of court and could well face a fine and a prison term.
If you want to draft the application then I can check it before you send it.
I hope this helps - if you can please accept the answer and give me a 5 star rating (there should be a button on your screen to do this), I can answer follow up Q&A's at no extra charge and Just Answer will credit me for helping you today.