You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I'm Matthew White. Because of post pone of my exams, I want to change my existing reservation. Can you please help me?

ASSISTANT: Yes Matthew, can you provide your airport codes?

USER: My travelling codes of airports are JFK and DTW.

ASSISTANT: Wait for a moment. Sorry, there is no reservation found with this name.

USER: Ok, that's fine. Thank you, for your information.

ASSISTANT: Thank you for reaching us.