You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Melissa Parker here.

ASSISTANT: How may I help you today?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, I will help you with that.

USER: Ok.

ASSISTANT: Please wait for a minute. I am sorry to say that there is no reservation found.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for reaching us.