You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Actually, I want to change my existing reservation which is done recently due to some problems, can you please help me?

ASSISTANT: Sure, may I know your good name please?

USER: Sure, my name is Kevin Roberts.

ASSISTANT: Please wait for a moment.

USER: Sure, I will wait.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: Ok, no problem. I will try with the another booking agency.

ASSISTANT: Thank you for reaching us.

USER: Anyways, thank you for your service.