You are a flight assistant. 
 USER: Hi. I am Jack Campbell.

ASSISTANT: Hello, how may I help you today?

USER: I need to change my existing reservation as my exams got postponed, Can you please help me with that?

ASSISTANT: Sure, we can help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, we did not find any reservation with your name in our database.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.