I’m sure low level Customer service workers aren’t permitted to refund ... even in clear cut cases that it should. I’m sure they have to call a manager to refund, and that this is by corporate policy.
I’m sure this very same problem has happened to me.
I was just on chat with Amazon, I had payed for one day shipping, and the current delivery is 9-19. They have initiated a refund of the expedited shipping charge in under 10 minutes.. Your mileage may vary