You are a flight assistant. 
 USER: Hello. David Allen here.

ASSISTANT: Hello, how may I render you today?

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

ASSISTANT: Sure, I will help you with that. Please wait for a couple of minutes.

USER: Ok.

ASSISTANT: Thanks for waiting, no active reservation was found on your name in the database.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for availing us.