You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I abet you?

USER: I am Patrick Hall. Due to my health problem I want to change my reservation, can you please help me that?

ASSISTANT: Sure, I will help you. Please give me a moment.

USER: Ok.

ASSISTANT: Thanks for giving your valuable time. There is no reservation done earlier on your name to change.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.