You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: Melissa Gonzalez here. I need to change my existing reservation as my sister blessed with a baby before the expected delivery date.

ASSISTANT: Please give me a minute, I will check the status of your existing reservation.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for contacting us, have a nice day.