As said SDColorado, stay calm, even friendly but explain them how this would be a problem for you to be without any Mac at the moment.
I for example was quit far away of any UPS point so I was sincerely not in capacity to send mine back before 10 days... The person I had on the phone had to reach a manager, but got a yes for a replacement without having to send mine back in first.
BTW, Apple Store have i9/32/1T in stock nearly everywhere worldwide for some reason. You may be able to swap it in an AS if you can reach one