You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, can you provide your name for checking?

USER: Myself Timothy Jackson.

ASSISTANT: Give me a minute.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation found under your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for choosing us.