You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Daniel Johnson.

ASSISTANT: How may I abet you today?

USER: I need to reschedule my existing reservation as my plan to go for a adventure trip got postponed. Can you help me in changing?

ASSISTANT: Sure, please wait a moment.

USER: Ok.

ASSISTANT: Sorry Daniel, there are no active reservations to change your journey.

USER: That's fine, thanks for your response.

ASSISTANT: Thank you reaching our service.