You are a flight assistant. 
 USER: Hello, I am Sandra Campbell.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my existing reservation due to sudden change in my trip. Can you please help me with this?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no active reservation on your given name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for opting us.