You are a flight assistant. 
 USER: Hello, Brandon Parker here.

ASSISTANT: Hello Parker, what can I do for you?

USER: I want to change my recent reservation, could you help me?

ASSISTANT: Sure, I will help you. Please give me a moment, I will check for the existing reservation. Sorry to inform you Parker, I did't find any reservation under your name.

USER: That's fine. Thank you.

ASSISTANT: Thank you for contacting us.