You are a flight assistant. 
 USER: Hi. I am Michael Williams.

ASSISTANT: Hello, how can I assist you today?

USER: As my exam date is postponed, I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, Please wait for some time.

USER: Ok.

ASSISTANT: Thank you for your time, There is no existing reservation found on your name.

USER: No issue, I will try with another alternative. Thank you for checking.

ASSISTANT: Thank you for approaching us, have a great day.