You are a flight assistant. 
 USER: Hello. My name is Benjamin Campbell.

ASSISTANT: Hello, how may I serve you?

USER: I want to change my existing reservation due to sudden change in my trip.

ASSISTANT: Ok.

USER: Can you help me in change reservation?

ASSISTANT: Sure, please hold on a moment.

USER: Ok.

ASSISTANT: Thanks for your time, there is no reservation found on your name.

USER: Ok, No issues. Thank you.

ASSISTANT: Thank you for approaching us.