You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, may I know your name for checking with your details.

USER: My previous reservation has done with my name Alexander Taylor.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Thank you for waiting. Sorry, there are no active reservations on your given name to change.

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

ASSISTANT: Thank you for reaching our service.