You are a flight assistant. 
 USER: Hi. I am Mary Rodriguez.

ASSISTANT: Hello, how exactly I can serve you the best today?

USER: Please change my existing reservation because, I postponed my travel due to my health issue.

ASSISTANT: Sure, we are here to help you. Please, stay online. I will check the previous list and revert to you.

USER: Ok.

ASSISTANT: Thank you for your valuable time.

USER: Ok.

ASSISTANT: We are sorry to inform you that, No reservation was found on your name to change.

USER: It's Ok, Thank you.

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