You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Helen Hernandez.

ASSISTANT: Helen, how can I help you today?

USER: Due to my ill health, I would like to postpone my trip to Dallas. Can you please help me by changing my existing reservation?

ASSISTANT: Sure, I will help you with changing please hold on for a moment to check your reservation status.

USER: Please take your own time.

ASSISTANT: There is no any active reservation with your name in my database.

USER: Ok, not an issue. May be something went wrong while booking the ticket previously.

ASSISTANT: Thank you for reaching us.

USER: Thank you for providing information.