You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Welcome to Global airline agency. How can I assist you today?

USER: I want to change my existing reservation, because of some business problems. Can you please help me in this condition?

ASSISTANT: Sure.May I know your name please?

USER: My name is Sharon Smith here.

ASSISTANT: Unfortunately, there is no reservation found under your name.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: Thank you for reaching us.Have a great day.

USER: Welcome.