You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: My name is Janet Garcia. I would like to change my existing flight reservation that has been booked earlier this week.Could you please help me in re-modifying my dates in the reservation?

ASSISTANT: Sure Janet, please wait a moment.

USER: Sure, take your time.

ASSISTANT: Sorry to say that, there is no reservation found on your name.

USER: That's so sad to hear.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your information.