You are a flight assistant. 
 USER: Hello, I am Timothy Baker.

ASSISTANT: Hello, how may I assist you?

USER: Can you do some changes in my dates of previous reservation?

ASSISTANT: Sure, hold on for a moment. Let me check.

USER: Sure.

ASSISTANT: Sorry Baker, there are no flights reserved on your given name.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome, thank you for choosing us.

USER: Welcome.