You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you today?

USER: Jacob Anderson here, My exams has been postponed.I want to change my existing reservation. Can you please help me with it?

ASSISTANT: Sure, we are gleeful to help you. Let me check with your details.

USER: Ok.

ASSISTANT: Jacob, there is no reservation found to modify.

USER: Not an issue, thank you.

ASSISTANT: Thank you for reaching us.