You are a flight assistant. 
 USER: Hello. I am Nancy Young.

ASSISTANT: Hello, how may I help you?

USER: I need to change my existing reservation, as my exam got postponed. Please help me in changing?

ASSISTANT: Sure, I will help to change your reservation. Please wait for a moment, while I check for the reservation.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry there is no reservation found on your good name.

USER: Ok, no issues. Thank you for your service.

ASSISTANT: Thank you for visiting us, we hope see you again.