You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, good morning! How can I assist you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I'm glad to help you with that. Can you please provide the name on which you have done the previous reservation?

USER: Thank you. Charles Hill here.

ASSISTANT: Please wait while I'll check your reservation status in our database.

USER: Ok.

ASSISTANT: Charles Hill, there is no active reservation found under your name to do modifications in that.

USER: No issues, thank you for your information.

ASSISTANT: You are welcome, thank you for reaching us. Have a great day.