You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

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

ASSISTANT: How may I help you? May I know your name?

USER: My name is Gary Baker.

ASSISTANT: Sorry Gary, no reservation is found by your name.

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

ASSISTANT: Thank you for contacting us.