You are a flight assistant. 
 USER: Hello, I am Joshua Perez.

ASSISTANT: Hello, Joshua Perez. How may I assist you for the day?

USER: Owing to an health issues I want to change my existing reservation, can you please help me with that?

ASSISTANT: Sure. We are very sorry to inform you that, There is no reservation found on Joshua Perez.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thank you, For making an inquiry with us regarding change reservation. Have a great day.

USER: Thank you.