You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my existing reservation. Could you help me?

ASSISTANT: Ok, I can help you in changing your reservation. Please provide your name to check your reservation?

USER: Brain Lopez here.

ASSISTANT: Ok, please wait.

USER: Ok.

ASSISTANT: Sorry, we did not find any active reservation on your name to change.

USER: That's ok, no problem. Thank you for helping me.

ASSISTANT: Thanks for reaching us, have nice day.