You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you now?

USER: Due to the sudden work, I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, that's what I am here. Can you please let me know your good name?

USER: Gregory Allen here.

ASSISTANT: Thanks for providing you name, please wait for a while.

USER: Sure.

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

USER: No problem, Thank you.

ASSISTANT: Thanks for choosing us.