I purchased 3 tickets in May, 2021 for a Covid tested flight from Chicago to Milan, Italy for July, 2021. At the time of purchase, each ticket was $400 more than the regular tickets to Milan. When, we departed Chicago, Delta did not require each passenger to be Covid tested. Therefore, we paid a premium to Delta for a service that was not delivered. Therefore, I would like a refund of the premium I paid for a service that was not delivered by Delta.