You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, Please inform me, how can I best aid you now?

USER: I am Melissa Martinez. Unfortunately my exams was changed so I want to change my reservation. Can you please help me that?

ASSISTANT: Sure, I can help you in that. Please wait for a while.

USER: Ok, I will wait.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: That's not a problem. Thank you.

ASSISTANT: Thanks for choosing us, we hope to serve you again.