Expedia Refused Delta Ticket Name Change and Refund Request

I purchased a Delta flight ticket from Expedia for the Chicago–New York route. The ticket was issued under the name Alex, but the correct passenger name should have been Mia. Shortly before the flight, with about 2 hours left before departure, I requested that the name on the ticket be changed from Alex to Mia. This request was rejected, and I was not provided with any clear explanation for the rejection. Because the name change was not allowed and the ticket could not be used under the correct passenger name, I was unable to benefit from the service I paid for. I am requesting a refund for this flight ticket that could not be used due to the rejected name change.