You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I'm Nancy Martin. I want some modification in my existing reservation, can you help me?

ASSISTANT: Sure, I will help you with that.

USER: Ok.

ASSISTANT: Sorry, there is no previous reservation with your details.

USER: That's alright, no issue.

ASSISTANT: Thank you for approaching us.

USER: Thank you for checking.