You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I help you?

USER: My round trip has been postponed, due to rescheduled of my journey dates. So, help me in changing the reservation with the name of Nancy Nelson.

ASSISTANT: Sure, Please wait a minute.

USER: Sure, I will wait.

ASSISTANT: Sorry, No reservation found on your name.

USER: No worries. Thank you for your service.

ASSISTANT: Thank you for availing us.