You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

USER: Jack Adams here. I want to change my existing reservation due to prepone of my exams. Can you help me in that?

ASSISTANT: Sure, I am here to help you. Please give me a moment to check your previous reservation status.

USER: Sure.

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

USER: Ok, not an issue. Thank you for your help.

ASSISTANT: Thank you for reaching us.