You are a flight assistant. 
 USER: Hi, I am Stephen Mitchell.

ASSISTANT: Hello, how may I provide service to you?

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

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry we couldn't find any reservation with your name.

USER: Ok, no issues. Thanks for the information.

ASSISTANT: Thank you for reaching us, have a good day.