You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Donna Baker.

ASSISTANT: How may I assist you Baker?

USER: I had planned to go on a vacation, but it was postponed.Can you change my recent reservation?

ASSISTANT: Sorry Donna, there is no reservation basing on your details.

USER: That's ok, no issues. Anyways, thank you for your service.

ASSISTANT: Most welcome.