It's very much a cultural thing. Japanese businesses rarely understand escalation. Their game is delayed so they sit on their hands with their thumbs up their asses being good boys and girls.
What they need to be doing is contacting them, demanding escalation to their supervisor. I know retards will scream "karen", but that's how it's done in the business world. You want something taken care of you keep escalating it till you waste the time of someone high enough that the people lower on the ladder shit the bed for fear of what will happen to them for their fucking around.