You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Dorothy Martinez.

ASSISTANT: Good morning Dorothy.

USER: I had planned to go on a vacation, but it was postponed. I am looking for changing of my reservation. Can you help me?

ASSISTANT: I will help you with changing the reservation.

USER: Ok.

ASSISTANT: Please be hold on for a moment to check whether the the reservation existing or not. Thank you for waiting. Sorry Dorothy, there is no reservation has found under your name.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Most welcome. Have a good day.