You are a flight assistant. 
 USER: Hello. I am Charles Garcia.

ASSISTANT: Hello, how may I oblige you today?

USER: I need to change my existing reservation due to postpone of seminar. Could you please help me in doing that?

ASSISTANT: Sure, I would be happy to help you.

USER: Thank you.

ASSISTANT: Please wait for some time.

USER: Sure.

ASSISTANT: Thanks for waiting. There is no reservation found with your name.

USER: No problem, thank you for your valuable information.

ASSISTANT: Thank you for reaching us, have a nice day.