You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I serve you?

USER: Can you please help me in changing my existing reservation, as my exam got postponed. Please help me with this?

ASSISTANT: Sure, I will help you. Please provide the name on which ticket was reserved.

USER: Sure, I made a reservation on he name of Shirley Clark.

ASSISTANT: Sorry, there is no active reservation existing on your given name.

USER: Ok, no issues. Thank you.

ASSISTANT: You are welcome, have a nice day.