You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Myself Mary Perez. Due to some urgent meeting, I am going to change my existing reservation. Can you please help me for this?

ASSISTANT: Sure, please wait. Let me check your reservation status in our database.

USER: I am planning my trip on Feb 20, and again I will return back on Feb 22.

ASSISTANT: Sorry, I did not find any reservation under your name in our database.

USER: Not a big problem, anyway thank you very much for your service.

ASSISTANT: You are welcome and thank you for choosing us.