You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation, because my leaves is not approved. So can you help me with it?

ASSISTANT: Sure, may I know your name please for further process?

USER: Yes, my name is Rebecca Taylor.

ASSISTANT: Ok, please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry Taylor, there is no reservation found on your name to change your reservation.

USER: That's ok, may be it is changed by my friend. Anyways thank you for assisting me.

ASSISTANT: Thank you for contacting us.