You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to change my reservation due to postponed of my exam, so please help me to modify my dates.

ASSISTANT: Sure, please provide me your name.

USER: Sure, I am Mary Garcia.

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Mary Garcia. I regret to inform that there is no reservation by your name.

USER: No worries, thank you.

ASSISTANT: Thank you for reaching us.