You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I oblige you today?

USER: I would like to change my existing reservation as my plan to go for a holiday trip got postponed. Can you please help me with this?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: My name is Sarah Carter.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for choosing us.