You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Kenneth Martinez.

ASSISTANT: How can I assist you today?

USER: As my exam is postponed, I want to change my reservation. Can you help me?

ASSISTANT: Sure, I will help you with that. Give me a minute.

USER: Ok.

ASSISTANT: Sorry to say that there is no reservation found.

USER: No problem, thank you.

ASSISTANT: Thank you for contacting us.