You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to change my reservation, due to some problems I am unable to travel those dates so can you please help me?

ASSISTANT: Sure, I will help you. May I know your name please?

USER: Thanks, my name is Amy Martin.

ASSISTANT: There is no previous reservation on your name in our database.

USER: Oh! It's ok no problem. Thank yo for your information.

ASSISTANT: Thank you for choosing us.