You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Unfortunately, I would like to change my existing reservation due to some problem, can you please help me in this intent?

ASSISTANT: Sure, can you please let me know your name to proceed?

USER: Sure, my name is Anna Scott.

ASSISTANT: Please give me a moment to check your details.

USER: Sure, take your time.

ASSISTANT: Sorry, no reservation found on your name.

USER: That's ok, thank you for checking.

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