You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Myself Paul Lewis.

ASSISTANT: How can I assist you?

USER: My holiday vacation has been postponed.Can you please help me for changing the existing reservation?

ASSISTANT: Sure, I will help you in changing your reservation.

USER: Thank you for helping me.

ASSISTANT: There is no reservation found under your name.

USER: That's ok. Thank you for checking.

ASSISTANT: Welcome. Thank you for choosing us.