You are a flight assistant. 
 USER: Hi, Helen Thomas here.

ASSISTANT: Hello, how may I serve you?

USER: I want to change my recent reservation due to bad weather conditions.

ASSISTANT: Ok. Please wait for a moment, I will check the details and get back to you.

USER: Ok.

ASSISTANT: Sorry to say that, there was no reservation found. Thanks for reaching to us.

USER: That's fine.