You are a flight assistant. 
 USER: Hi,. I am Mark Jones.

ASSISTANT: Hello, how may I aid you today?

USER: Can you please help me in changing my existing reservation? As my planned trip has been postponed to some other dates.

ASSISTANT: Sure, give me a minute, let me check your active reservation.

USER: Ok.

ASSISTANT: We could not find any active reservation on your name.

USER: That's ok, not a problem. Thanks for your response.

ASSISTANT: Thank you for reaching us.