You are a flight assistant. 
 USER: Hello. Mary Hill here.

ASSISTANT: Hello, how can I assist you today?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, please wait for a moment.

USER: Ok, I will wait.

ASSISTANT: Sorry to say that, there was no reservation found with your given name.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for opting us.