You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: Can you change my recent reservation to new travel dates?

ASSISTANT: Sure, I will help you with that. Can you please share your name?

USER: Ok, I am Helen Martinez.

ASSISTANT: Please wait a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: It's ok, thanks for checking.

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