You are a flight assistant. 
 USER: Hi, I am Charles Martinez.

ASSISTANT: Hello, how can I provide assistance to you?

USER: Owing an emergence, I want to change my existing reservation. Can you please help me with it?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Just wait a moment, I will check your details and let you know the current status.

USER: Ok.

ASSISTANT: Sorry to inform you that there is no reservation found on your name to proceed further.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: Thank you for contacting us.