You are a flight assistant. 
 USER: Hello. I am Lisa Robinson.

ASSISTANT: Hello, how can I assist you today?

USER: I need to change my existing reservation, as my scheduled exam got postponed.

ASSISTANT: Ok.

USER: Please help me in changing?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait for a while, I will check your previous reservation.

USER: Ok.

ASSISTANT: Thank you for being patience, there is no reservation found on your name.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for contacting us.