You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Gregory Martinez.

ASSISTANT: How may I assist you today?

USER: I want to change my departure details in my existing reservation, could you please help me out?

ASSISTANT: Sure, please wait for a minute.

USER: Ok.

ASSISTANT: Sorry, I cannot find any reservation with your name.

USER: No problem. Thank you for your help,.

ASSISTANT: Thanks for contacting us.