You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: My name is Brian Parker. Due to sudden changes in my schedule, I want your help in changing my existing reservation. Can you please help me with that?

ASSISTANT: Sure, please wait for a mean while.

USER: Ok.

ASSISTANT: Sorry Parker, there is no reservation found as per your name to change your reservation.

USER: That's ok, thank you for your service.

ASSISTANT: You are welcome and hope you have a great day.