You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: Owing an emergence, I want to change my existing reservation. Can you help me with it?

ASSISTANT: I will surely help you in that. Can I have your name to check your previous details?

USER: My name is Nancy Young.

ASSISTANT: Nancy, please wait. Sorry to say that, there is no active reservation found under your name.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: You are welcome. Thank you for choosing our service.