You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

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

ASSISTANT: I will help you with that. Please wait, I will check your reservation and let you know. May I know your name?

USER: Sure, my name is Jason Campbell.

ASSISTANT: Sorry, I have not found any reservation on your name in our database.

USER: Ok, that's fine. I will try with the another travel booking agency. Anyways, thank you for your service.

ASSISTANT: You are most welcome and thank you for choosing us.