You have tjreatened to call the police. His reaction is: " OK go ahead". You then ring up the police station and a police car comes round.You explain the situation.The police sergeant says he can do nothing - this is not a criminal case, so the police won't prosecute.
"If you want to take your neighbour to court," says the sergeant, "you'll have to do it yourself".
You feel so angry and digusted that you decide to do nothing.