can i see someones (account) other characters?

hi, so theres a player who sends me large amounts of annoying whispers from his various characters and at the same time ignoring me
long story short, he just doesnt speak english very well and after having a short discussion with him (we werent arguing or anything, my last sentence was something like "thats normal"), he somehow misunderstood what i was saying, whispered me "im not your teacher pay me" (i was like wtf?), ignored me and that was the end of it
no problem with me then, but now he is sending me funny/irritating whispers from all his characters and so far i must have already ignored like a dozen of them
i have no idea what he thinks i told him but its becoming really annoying
is there any way to find out the rest of his characters so i can ignore them all at once?

you can report him by opening a ticket in-game.

His behavior to keep whispering you with different characters to avoid /ignore is bannable