You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: I want to change my existing reservation due to postpone of my meeting. Can you aid me?

ASSISTANT: Sure, Can you help me with your good name please?

USER: Mark Harris is my name.

ASSISTANT: Please wait a while. I will check and get back to you.

USER: OK.

ASSISTANT: Unfortunately we didn't found any reservation matching your name.

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

ASSISTANT: Thank you for reaching us.