You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I am Melissa Lee, help me to change my reservation as my plan to visit Houston for a vacation has been postponed.

ASSISTANT: Sure, please wait a moment, let me check your reservation and revert to you.

USER: Sure.

ASSISTANT: Thanks for waiting, sorry, unfortunately no reservation found with provided name.

USER: Thanks for the information.

ASSISTANT: Thanks for your interest, have a great day ahead.