You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I support you today?

USER: I want to change my existing reservation due to sudden postpone of my exam dates. Can you help me with that?

ASSISTANT: Sure, please share me your good name.

USER: Donna Baker here.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Sorry to say that, there is no active reservation found on your good name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for your information.