You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What type of service you are excepting from us?

USER: I am trying to modify my travel dates in the past ticket. Can you please help me in changing the ticket details?

ASSISTANT: Sure, I am here to help you.

USER: Thank you for accepting my request.

ASSISTANT: Sorry to say that, there is no reservation found on your name in our database. Can I know your name?

USER: It's ok, not a problem. Thank you. My name is Andrew Taylor.

ASSISTANT: Thank you for reaching us.