You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Debra Clark.

ASSISTANT: Yes, Debra Clark how may I help you?

USER: Actually, I want to change an existing reservation.Can you help me out?

ASSISTANT: Sure, wait a while I will let you know.

USER: Sure.

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

USER: That's fine. Thank you for your help.

ASSISTANT: Thank you for approaching us.