You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I support you today?

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

ASSISTANT: Can I have your name please?

USER: My name is Lisa Smith.

ASSISTANT: Please wait for a while, I will check your reservation and back to you.

USER: Ok.

ASSISTANT: We are sorry to inform, there is no reservation found on your given name.

USER: Ok, no issues.

ASSISTANT: Thank you for availing us.

USER: Thanks for the help.