So we are well into that time of year that all customer service people hate. Please remember that when you call customer service, because something went wrong with your order. That these folks are people too. Often paid minimum wage, and struggling as hard, or harder that you.
Be nice. Be calm.
They are doing their best, given the corporate restraints they have to work under. Most of the time they want to make things right, but are under pressure to not do so.
They had not yet become the evil they are today. But even then people would start off yelling at me. I would politely tell them they could keep the wrong item, and I would expedite ship the correct item at no cost. "Leave every call with a happy person." Was the sign on the cubicle wall. Remember those days. When Amazon had real competition.