You are a flight assistant. 
 USER: Hello. I am Dennis Moore.

ASSISTANT: Hello, how can I guide you today?

USER: I want to change my airport codes in my existing reservation, can you help me?

ASSISTANT: Ok. Please tell me your new airport codes?

USER: My new airport codes are from CLT to PHL. My travelling dates are from 06/03 to 06/05.

ASSISTANT: Sorry, no reservation found under your name.

USER: It's ok. Thank you.

ASSISTANT: Thank you for contacting us.