You are a flight assistant. 
 USER: Hello. I am Joseph Young.

ASSISTANT: Hello, how may I assist you today?

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

ASSISTANT: Sure, we are here to help you. Please wait for a while.

USER: Ok.

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

USER: Ok, no issues.

ASSISTANT: Welcome, thank you for reaching us.

USER: Thank you.