You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is David Perez.

ASSISTANT: David, how can I assist you?

USER:  I am having sudden meeting in my office, can you please help me changing my reservation?

ASSISTANT: Sure, I am here to help you. Let me check your reservation status in our database.

USER: Ok, take your time.

ASSISTANT: David, I have not found any reservation under your name in our database.

USER: It's ok, no problem. Thank you for checking.

ASSISTANT: You are welcome and have a nice day.