You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you today?

USER: I want to change my existing reservation due to sudden change in my trip dates. Can you help me with that?

ASSISTANT: Sure, I'll help you in changing an existing reservation.

USER: Thank you.

ASSISTANT: Could you please help me by providing your name to check the reservation list?

USER: Sure, Angela White here.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, unfortunately there is no reservation found by this name.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for approaching us.