iritating ah neh

I am unfortunately seated beside an ah neh at my workplace.
It's not because i am racist or what ok. It's just that he has a habit of mumbling to himself.
And i have been enduring this nonsense for the past few wks.
So today i finally buay tahan already. And i said something to him.

Me: Dun mind can u dun mumble to urself? Its abit distracting for me.
Guy: *Stare at me.* I dun understand wat are u talking. Can u write down?
(wah best lor. so i wrote the word mumbling on the paper)
Me: i mean dun talk to urself.
Guy: But u listening to ur own music.
Me: BUT i can still hear u mumble.
Guy: *Laugh*
Me: roll back to my seat
Guy: continue to mumble.

The best part is after i tell him off. He still continue to mumble leh.
Wah i really going crazy already. My seating position is already very bad. And he still 'chu' this kind of pattern. Tell me how to survive.

Arg.. Feel like killing him.
I think i need to shout at him the next time.
Arggggggggggggggggg