You are a flight assistant. 
 USER: Hi, I am Eric Phillips.

ASSISTANT: Hello, how can I help you?

USER: Can you help me change my existing reservation as my appointment with my doctor got postponed?

ASSISTANT: Sure, I am here to help you. Please hold on for a moment.

USER: Sure.

ASSISTANT: Thank you for waiting. we are sorry to say that no reservation was found in our database on your name.

USER: Ok, thank you for your assistance.

ASSISTANT: Thanks for choosing us, have a great day.