You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Jacob Smith.

ASSISTANT: How may I guide you today?

USER: I want to change my existing reservation due to postpone of my exams so, can you please help me in changing my reservation?

ASSISTANT: Sure, I am oblige to help you with that. Please wait a moment to check your previous reservation status.

USER: Sure.

ASSISTANT: We regret to inform you that, there is no reservation found on your name in our records.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for reaching to our services, hope you have a great day.