You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I best service you now?

USER: I am Donald Miller. Owing to an emergency I want change my existing reservation, can you please help me with that?

ASSISTANT: Sure, we are here to help you. Please stand by I will get back to you.

USER: Sure.

ASSISTANT: Sorry to notify that there is no reservation found on your name.

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

ASSISTANT: Thanks for opting us.