You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I address you today?

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

ASSISTANT: Ok. To change your reservation I need to know your name.

USER: I am Samuel Miller .

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, no reservation found with your name to change the reservation.

USER: No issue. Thank you for your service.

ASSISTANT: Thanks for choosing our agency.