You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: My name is Jennifer Johnson, I want to change my existing reservation due to postpone of my family tour trip.

ASSISTANT: Please wait for a while, let me check your details.

USER: Sure.

ASSISTANT: Sorry Jennifer, there is no reservation found under your name.

USER: No problem, thanks for your help.

ASSISTANT: Thank you for reaching us.