You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Larry Martinez here.

ASSISTANT: How can I assist you today?

USER: I want to change my existing reservation. Can you help me in that?

ASSISTANT: Sure, I can help you with that. Please wait for a while.

USER: Sure.

ASSISTANT: Larry Martinez, there is no reservation found active under your name to do modifications in that.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing us, have a nice day.