You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Samantha Perez here.

ASSISTANT: How may I aid you today?

USER: I would like to change my reservation due to health issue.

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Ok, take your time.

ASSISTANT: We regret that, there is no reservation with your name in our records.

USER: It's ok, no problem.

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

USER: Thank you.

ASSISTANT: Welcome.