You are a flight assistant. 
 USER: Hello. I am Shirley Lewis.

ASSISTANT: Hello, How may I assist you today?

USER: I need to change my existing reservation, as my exam got postponed. Please help me in changing?

ASSISTANT: Sure, can you give me a minute to check with the reservation list?

USER: Ok.

ASSISTANT: Thanks for waiting, we are sorry to say you that, your name is not found in our database.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for choosing us.