You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you today?

USER: Please help me to update my travelling dates in by existing reservation.

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Could you please provide your name to proceed further?

USER: I made a reservation by this name Donald Lee.

ASSISTANT: Ok, please wait for a minute.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no active reservation found on your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.