You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Myself Gary Martinez. Can you please change my existing reservation ?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found with your given name.

USER: Ok, that's fine for me. I will choose an alternative. Thanks for your service.

ASSISTANT: Thank you for opting us.