You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am planning to change my existing reservation. Can you please help me for this?

ASSISTANT: Yes, can you share me your name?

USER: Myself Janet Walker.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Not a big issue, anyhow thank you very much for your kind information.

ASSISTANT: Thank you for reaching us.

USER: You are most welcome.