You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: Owing an emergence, I want to change my existing reservation. Can you help me with it?

ASSISTANT: Sure, we are happy to help you. May I know your name please?

USER: My name is Samuel Carter.

ASSISTANT: Ok, Samuel Carter, please give me a minute.

USER: Sure.

ASSISTANT: Thanks for your time, we are sorry to say that no reservation was found in our database with your name.

USER: Ok, no issues.

ASSISTANT: Thanks for reaching us, we hope to serve you again.

USER: Thanks for the help.