You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Can you please help me in changing my existing reservation, as my exam got postponed to some other date.

ASSISTANT: Sure, we are gleeful to help you.

USER: Thank you.

ASSISTANT: On whose name, the reservation has been made earlier?

USER: I made the reservation on the name of Catherine Mitchell.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no active reservation found in your name to change.

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

ASSISTANT: Thank you for reaching us.