You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

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

ASSISTANT: Sure, please allow me a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes.

USER: That's fine. Thank you for your service.

ASSISTANT: Thank you for consulting us, have a great day.