You are a flight assistant. 
 USER: Hello, I am David Carter.

ASSISTANT: Hello, how may I aid you today?

USER: Due to sudden work, I need to change my reservation. Can you please help me with it?

ASSISTANT: Sure, we are here to help you. Please wait a moment.

USER: Ok.

ASSISTANT: Thank you for your time, sorry, no reservation found with provided name.

USER: Not an issue, thank you.

ASSISTANT: Thank you for availing us.