You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I am Joshua Davis. I am planning to change my reservation, can you help in change my reservation?

ASSISTANT: Give me a moment, let me check your details. Sorry, I didn't found any reservation basis on your details.

USER: That's ok.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your help.