You are a flight assistant. 
 USER: Hello. I am Donna Nelson.

ASSISTANT: Hello, do you need any help from us?

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

ASSISTANT: Sure, please allow me a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: You are welcome.