You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: My name is Sandra Roberts. I want to change my existing reservation due to bad weather condition.

ASSISTANT: Sure, wait for some time.

USER: Ok.

ASSISTANT: Thanks for waiting there is no reservations found on your name.

USER: No problem, thank you for your service.

ASSISTANT: Thanks for choosing us.