You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

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

ASSISTANT: Sure, I am happy to help you and can you please mention your previous flight ticket booking name for checking purpose?

USER: Myself Timothy Roberts.

ASSISTANT: Please allow me a moment to check it.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for being on hold, there is no reservation found for the user name in our data base to change your previous flight ticket booking.

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

ASSISTANT: You are most welcome and thank you for approaching us, have a nice day.