You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: My name is Jennifer Mitchell. I would like to postpone my trip dates, could you help me in changing my existing reservation?

ASSISTANT: Sure, plaease wait for a minute.

USER: Sure, take your time.

ASSISTANT: Unfortunately there is no reservation found with your name to change it.

USER: That's ok.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your time.