You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: Can you please change my existing reservation?

ASSISTANT: Sure, I am here to help you. Can you please share your name to check further in our database?

USER: Thank you for your response, I am Stephanie Hernandez.

ASSISTANT: Please wait.

USER: Ok.

ASSISTANT: Sorry, no reservation found on your given name in our database to change it.

USER: It's ok, thank you for checking.

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