You are a flight assistant. 
 USER: Hello. My name is Eric Collins.

ASSISTANT: Hello, how can I assist you today?

USER: My appointment with family my doctor got postponed. So, Can you help me to change my existing reservation?

ASSISTANT: Sure, please wait for moment.

USER: OK.

ASSISTANT: Thanks for waiting. Sorry, no reservation found with your name.

USER: OK.

ASSISTANT: Thank you for choosing us.

USER: Thank you, For helping me.