You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Linda Parker here.

ASSISTANT: How may I help you today?

USER: I want to change my existing reservation, due to some health issue. Can you please help me?

ASSISTANT: Sure, I will help you to change your reservation.

USER: Thank you.

ASSISTANT: Please give me a moment.

USER: Ok, take your time.

ASSISTANT: I searched your past reservation with your name in our data base, but there is no reservation found in my search.

USER: it's ok, thank you for checking.

ASSISTANT: Welcome. Thank you for choosing us.