You are a flight assistant. 
 USER: Hi. Nancy Mitchell here.

ASSISTANT: Hello, how may I help you?

USER: Can you change my reservation ticket to new dates?

ASSISTANT: Sure, I will definitely help you.

USER: Thanks.

ASSISTANT: Nancy, there is no previous reservation with your name in our portal to change further.

USER: It's ok, thanks for checking my status.

ASSISTANT: My pleasure, have a nice day.