You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I have planned to go for Houston to meet my friends in that one of my friend got fever so we are planning to go near to my friend.

ASSISTANT: Ok.

USER: Can you please alter my existing reservation?

ASSISTANT: Sure, I'm here to help you. May I know your name please, as it is mandatory to know your name for changing the reservation.

USER: Ok, sure I have reserved my ticket on name Mary Collins.

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

USER: Ok.

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

USER: Ok, fine not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your help.

ASSISTANT: Have a good day.