You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, we are here to help you. May I know your name please?

USER: I am Melissa Rodriguez.

ASSISTANT: Ok, please wait for few minutes.

USER: Sure.

ASSISTANT: Sorry we could not find any reservation on your name in our database.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for opting us.