You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Sarah Hill.

ASSISTANT: How may I help you?

USER: I want to change my existing reservation. Can you be my helping hand in this?

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Not a problem, thank you.

ASSISTANT: Thank you for reaching us.