You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How ,may I guide you today?

USER: I would like to change my existing reservation. Will you help me with this?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Donald Walker.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: Ok, not an issue. May be something went wrong while making the reservation.

ASSISTANT: Thank you for reaching us.

USER: Anyways, thank you for providing information.