You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I be of your assistance?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: sure, I'll try to change an existing reservation. Can I have your name to check the reservation list?

USER: Kenneth Lopez here.

ASSISTANT: Thank you for giving your name, please give me some time.

USER: Sure.

ASSISTANT: Thank you for waiting, I have checked the reservation list to change your ticket but there is no reservation found by this name.

USER: It's ok, thank you.

ASSISTANT: Thank you for approaching us.