You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Melissa Thompson.

ASSISTANT: How can I serve you today?

USER: I want to change my existing reservation reservation. Can you please help me with this?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait a second. I will check the update.

USER: Sure.

ASSISTANT: There is no reservation found under your name to change.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for opting us.