You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I am Cynthia Smith. I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, please wait for a minute.

USER: Thank you. Ok.

ASSISTANT: Sorry for the trouble which is caused to you, there is no reservation found with your name in our system data to change the travelling dates.

USER: No issue. I will choose other alternative.

ASSISTANT: My pleasure.

USER: Thank you for the information.