You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation with the name of Janet Hernandez. Can you help me in this?

ASSISTANT: Sure, please wait for a while, I will check and get back to you.

USER: Ok.

ASSISTANT: Sorry, no reservation found with your name.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for choosing us.