You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you at this moment?

USER: I need to change the travel dates in the previous reservation because I have postponed my trip. Can you please help me to do that?

ASSISTANT: Sure, I am here to help you. Can I know your name please?

USER: Thank you. I am Michael Turner.

ASSISTANT: Sorry to inform you that, there is no active reservation found with your name to change the ticket details.

USER: That's fine, no problem.

ASSISTANT: You are most welcome. Thank you for choosing us.

USER: Than you for your help.

ASSISTANT: My pleasure.