You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Ok, may I know your name?

USER: My name is Janet Harris.

ASSISTANT: Ok, please allow me to check with availability.

USER: Ok.

ASSISTANT: Sorry, no reservation was found by your name.

USER: Ok, no issues.

ASSISTANT: Thank you for choosing us.

USER: Thank you.

ASSISTANT: Have a nice day.