Ok, you can write to the neighbour and ask them to stop.
If they refuse then you can get a local Solicitor to write and ask them to stop or say you will go to Court.
If that does not work then you can issue proceedings using form N1:
The court will list the matter down for a hearing and decide whether to grant an injunction preventing parking,
If the Court does and they continue to park, then this could be contempt of Court, which they may be warned, fined or sent to prison.
Can I clarify anything for you about this today, please?
If not, I would appreciate a 5-star rating for my answer. If you need anything further I am available for a follow up at no extra cost.