The story opens with the teacher (I can't remember his name, so call him 'Whosit') stranded because his 'new' car has died, phoning the salesman, hoping for redress, and being blown off.
Suddenly the world turns on the salesman: at first amusingly, but then it snowballs into horror — we see the salesman's wife walking out, saying only "Whosit doesn't like you" — and though he attempts redress, he winds up dying by the side of the road while people mock him.
Then we see the music teacher, receiving a call from the student who's appointment he'd missed, and although he tries to apologize, it is clear that the weight of the world is about to descend on him in his turn!
I've often remembered this story as a clever parable about the danger of revenge fantasies. I believe I read this is some American collection in the seventies or eighties.