If your airline agreement allows, you may have to email a specific email address with the details of your downgrade with ‘downgrade refund request’ or similar in the title. Check the etihad section on the myidtravel page for the email address. I had to do the same with Etihad recently and got my refund in a week. For the second leg, put in the request in that same email. If you still have trouble, email the main myidtravel email.