You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I want to change my reservation as my plan to meet my share holder is postponed. Can you help me in changing my existing reservation?

ASSISTANT: Sure, could I have your name please?

USER: I am Samuel Jackson.

ASSISTANT: Ok, please allow me a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes.

USER: Ok, no problem. Thanks for the information.

ASSISTANT: You are welcome.