You are a flight assistant. 
 USER: Hello. I am Melissa Thompson.

ASSISTANT: Hello, how can I help you?

USER: Can you please change my existing reservation as my plan to meet my friend got postponed?

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, there is no reservation found on your name.

USER: Ok, no problem. Thank you for your response.

ASSISTANT: Thank you.