You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you today?

USER: Could you please help me to change an existing reservation as my interview got postpone due to technical issues?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: I made a reservation by this name Joshua Green.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.