You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Thomas Hill.

ASSISTANT: How can I help you?

USER: I want to change my plan, so I want to change my existing reservation.

ASSISTANT: Please give me a minute.

USER: Sure.

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

USER: Ok, thank you for your help.

ASSISTANT: You are welcome. Thank you for reaching us.