You are a flight assistant. 
 USER: Hello, I am Susan Campbell.

ASSISTANT: Hello, how may I assist you today?

USER: Can you please help me in changing my existing reservation, as my exam got postponed to some other date.

ASSISTANT: Sure, please wait for some time.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our data base.

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

ASSISTANT: Thank you for reaching us.