You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you today?

USER: I want to do some changes in my existing reservation Can you help me for that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Can you share your name to check for the reservation in our portal?

USER: My name is Benjamin Walker.

ASSISTANT: Sorry, no reservation found on your name in our portal to change it.

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

ASSISTANT: Thank you for reaching us.

USER: Welcome.