You are a flight assistant. 
 USER: Hi, I am Charles Edwards.

ASSISTANT: Hello, how may I assist you?

USER: Owing to an emergency, my meeting with client has been postponed. So I need to change my existing reservation, can you help me with that?

ASSISTANT: Please wait a moment, let me check and back to you.

USER: Sure.

ASSISTANT: Unfortunately, no reservation found on your given name.

USER: Ok, no issues.

ASSISTANT: Thank you for communicating with us.

USER: Thanks for your assistance.