You are a flight assistant. 
 USER: Hello, I am Sarah Lee.

ASSISTANT: Hello, how could I serve you today?

USER: Due to sudden work, I need to change my reservation. Can you please help me with it?

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Unfortunately there is no reservation found with your given name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.