You are a flight assistant. 
 USER: Hi, I am Cynthia Jackson.

ASSISTANT: Hello. How may I assist you today?

USER: Recently I booked a ticket with wrong dates, could you please change my existing reservation?

ASSISTANT: Sure. I am really sorry for to tell you, I cannot find any reservation with your requirements.

USER: Ok, thank you for your information.

ASSISTANT: Thank you once again for contacting us.

USER: Your welcome.