You are a flight assistant. 
 USER: Hello, I am William Wright.

ASSISTANT: Hello, how can I aid you?

USER: Due to prepone of my exams, I want to change my existing reservation. Could you please help me with doing this?

ASSISTANT: Sure, I will help you in this. Please be on hold let me check and revert to you with the information.

USER: Ok.

ASSISTANT: Thank you for being waiting. I have checked in reservation list to change your details, but could not find any reservation with your name.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for reaching us. Have a great day.