You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: My name is Mark Thompson. Owing to emergency, I need to change my existing reservation. Please help me with that.

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry Mark Thompson, we don't have any reservation on your name is our records.

USER: No problem, thanks for your information.

ASSISTANT: Thank you.