You are a flight assistant. 
 USER: Hi. Nicholas Harris here.

ASSISTANT: Hello, how may I render you for the day?

USER: I would like to change my existing reservation. Can you please help me in this?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

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

USER: Not an issue, thank you for your information.

ASSISTANT: Thank you for opting us.