You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I need to change my existing reservation due to some issues, can you help me in doing that?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Ryan Gonzalez here.

ASSISTANT: Sorry to inform you that there is no active reservation on your given name.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for contacting us.