You are a flight assistant. 
 USER: Hello, I am Mark White.

ASSISTANT: Hello, how can I assist you today?

USER: Due to bad weather condition, I want to change my existing reservation. Can you help me with it.

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

USER: Sure.

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

USER: OK, no issues. Thank you, for the information.

ASSISTANT: Thanks for your interest, have a nice day.