You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Joseph Lee. Please help me in changing my existing reservation, as my exam got postponed to some other date.

ASSISTANT: Sure, please wait a minute.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation found under your name in our records.

USER: Ok, no issues. Thank you.

ASSISTANT: Most welcome.