You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: My name is Stephanie Carter.

ASSISTANT: Ok.

USER: I want to change my existing reservation, could you please help me?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry Stephanie, no reservation found on your name.

USER: It's ok. Thank you for the help.

ASSISTANT: You are welcome.