You are a flight assistant. 
 USER: Hello. I am Donna Carter.

ASSISTANT: Hello, how can I provide assistance you today?

USER: Owing to an emergency, I need to change my existing reservation,. Please help me in changing?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to inform, no reservation found with your name.

USER: Ok, no issues. Thank you for your help.

ASSISTANT: Thanks for reaching us.