You are a flight assistant. 
 USER: Hi. I am Nicole Turner.

ASSISTANT: Hello, how may I assist you?

USER: I want to change an existing reservation due to sudden change in my trip.Can you help me?

ASSISTANT: Sure, I will help you. Please wait for a second.

USER: Ok.

ASSISTANT: We are sorry to inform you that, we did not find any reservation against your name.

USER: No issue. Thank you for your help.

ASSISTANT: Thanks for using our service.