You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is James White.

ASSISTANT: Can you please tell me how can I assist you?

USER: I want to change my departure day in my existing reservation. Please help me in changing process.

ASSISTANT: There is a possibility to change your reservation, can you please tell me your details that you want to update?

USER: Ok. My origin is from CLT on 01/16.

ASSISTANT: May I know your destination details?

USER: My destination is from LGA on 01/18.

ASSISTANT: Sorry to say no flights found on your dates.

USER: It's ok, thank you for your quality service.

ASSISTANT: You are welcome. Thank you for choosing us.