You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I would like to change my existing reservation. Please help me out.

ASSISTANT: May I know your name?

USER: Sure, my name is Margaret wright.

ASSISTANT: Margaret, please give me a moment to check your ticket status.

USER: Sure, take your time.

ASSISTANT: Sorry, no reservation is available by your name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for contacting us.