You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Dennis Garcia.

ASSISTANT: How may I serve you?

USER: I want to change my existing reservation due to heavy rainfall, so please change my existing reservation.

ASSISTANT: Sure, please hold on.

USER: Ok.

ASSISTANT: Thanks for being on hold, there is no active reservation on your name.

USER: No problem, thank you.

ASSISTANT: Thanks for consulting us, hope to serve you again.