You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your good name?

USER: David Carter here.

ASSISTANT: What kind of service you are expecting from me?

USER: Due to an emergency, I want to change my recent reservation. Can you help me?

ASSISTANT: Sure, please be on hold.

USER: Ok.

ASSISTANT: Sorry, we did not find any reservation with your name.

USER: No problem.

ASSISTANT: Thanks for reaching us.

USER: Thank you for quick reply.