You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I guide you?

USER: I booked a refundable flight ticket previously. I am willing to change my ticket due to some virus is spreading in the place where I planned to visit. Can you change my existing reservation?

ASSISTANT: Sure, I will check your previous ticket. Before that can you please tell me your name to check your previous reservation?

USER: My name is John Williams.

ASSISTANT: Ok John, please hold on for a while.

USER: Sure, take your time but please try to change my existing reservation.

ASSISTANT: Sure, I will try to change your reservation.

USER: Thank you.

ASSISTANT: Sorry John, I did not find any reservation on your name in our database.

USER: That's ok. Thank you for checking.

ASSISTANT: You are welcome.