You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I support you?

USER: I am David Parker from Chicago. I have made a reservation for a long trip with my friends to Washington, Unfortunately some of my friends are unable to travel. Can you help me in Changing my reservation?

ASSISTANT: Sure, please give me a minute.

USER: Sure, I will wait.

ASSISTANT: I am sorry to inform that there is no reservation found with your name in our database.

USER: That's ok, not an issue.

ASSISTANT: Thanks for availing us.

USER: Thank you for your information.