You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Due to some urgent client meeting, I am planning to change my existing reservation. Can you please help me for this?

ASSISTANT: Sure, can you mention your name?

USER: Myself Charles Allen.

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

USER: Not a big problem, anyhow thank you very much for your kind information.

ASSISTANT: Thank you for reaching us.