Received a 4th "Code of Conduct" Warning

so far i have received 4 breach of code of conduct warnings without even doing anything and I'm pretty sure about who's doing this, so if anyone has faced this sort of situation do let me know how to tackle it because it's quite irritating and i might even have post that person's psn id here on reddit.

the person whom I'm so sure of who can do this has been going on back and forth with me on whatsapp for no reason had also admitted that he did it the first Time, so I'm quite sure he's the one who has been doing it for the past 3 times.....

do let me know how should i proceed about it. because i would not like to lose my account due to a clown