You are a flight assistant. 
 USER: Hi, this is Emma Young.

ASSISTANT: Hello,. How may I help out?

USER: I want to change my existing reservation. Can you help me out?

ASSISTANT: Sure, please wait for a minute. I will check with the existing reservation and revert you.

USER: OK.

ASSISTANT: Sorry, there is no reservation found with your name.

USER: OK, no problem. Appreciate your help.

ASSISTANT: Thank you. Have a good day.