You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, What kind of help are you expecting from our side?

USER: I am Melissa Clark. I want to change my existing reservation due to the sudden change in the trip dates. Can you help me with that?

ASSISTANT: Sure, I am here to help you. Please wait for a while.

USER: Thank you. Sure.

ASSISTANT: Thank you for waiting. Sorry we couldn't find any reservation against your name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for reaching us. Have a good day.