You are a flight assistant. 
 USER: Hello. I am Sandra Davis.

ASSISTANT: Hello, how can I serve you?

USER: As my exams got preponed I need change my reservation to another dates. Can you please help me?

ASSISTANT: Sure, please wait a minute.

USER: Ok.

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

USER: Ok, thank you.

ASSISTANT: Thank you for reaching us.