AppleCare warranty refund not received after returning damaged iPhone

I had to send my iPhone to Apple due to damage (through AppleCare warranty) and received a replacement. I was told they would take $1800 (or so) out of my account and refund when the damaged device was returned. I can’t find any information about either transaction and don’t think I’ve been refunded (even though it was returned within the timeframe). Any ideas of what to do or how to find out more information?!

[Re-Titled by Moderator]

Original Title: Refund after returning device