You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Angela Clark.

ASSISTANT: How can I serve you?

USER: Please help me to change an existing reservation as my plan to meet my grand parents got postpone.

ASSISTANT: Sure, we are euphoric to help you.

USER: Thank you.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: Thank you for waiting, but I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for consulting us.