You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you out?

USER: I want to change my existing reservation which is done recently due to some health issues, can you please help me?

ASSISTANT: Sure, I will help you in changing the ticket.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Sure, my name is Robert Allen.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: Ok, no problem. Anyways, thank you for your service.

ASSISTANT: Thank you for choosing us.