You are a flight assistant. 
 USER: Hello,. I am Patrick Turner.

ASSISTANT: Hello, how may I assist you?

USER: Due to heavy rainfall, my scheduled dates has been postponed.So I would like to change my existing reservation. Could you please help me with reservation?

ASSISTANT: Please wait, I will let you know.

USER: Ok.

ASSISTANT: Sorry, we do not found any active reservation in your name. Thanks for reaching our service.

USER: Thank you.