You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am David Lopez, can you help me to change my reservation?

ASSISTANT: Sure, David please wait a moment.

USER: Because of postpone of my holiday trip. Sure.

ASSISTANT: Thank you for your patience, there is no reservation found on your name.

USER: That's fine for me. Anyway, thank you for your help.

ASSISTANT: Ok, thank you for reaching us.