You are a flight assistant. 
 USER: Hello, myself David Martin.

ASSISTANT: Hello David, how may I aid you?

USER: May I know if can you change my existing reservation to some other locations?

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

USER: That's good to hear from you.

ASSISTANT: Please allow me a moment to check your reservation details.

USER: Ok, take your time.

ASSISTANT: Sorry David, there is no active reservation on your name in our records.

USER: That's ok, not a problem may be it is been changed by my family members. Anyways thank you.

ASSISTANT: Thank you for contacting us.