You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: As my meeting got postponed, I would like to change my existing reservation. Can you help me with this?

ASSISTANT: Sure, may I know your name please to check the reservation status?

USER: My previous reservation has done with the name Charles Thompson.

ASSISTANT: Charles, I couldn't find any reservation with your details.

USER: Ok, not an issue. May be something went wrong while booking the ticket. Thank you for providing information.

ASSISTANT: Thank you for contacting us.