You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Gary Hall.

ASSISTANT: How can I help you?

USER: I am planning to change my reservation, can you help me in booking a flight?

ASSISTANT: Sure, can you give me your name for checking?

USER: I mentioned already?

ASSISTANT: Sorry, there is no reservation found under your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.