You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you?

USER: I want to change my existing reservation due to some problems, can you please help me in this condition?

ASSISTANT: Sure, I will help you. Can you please tell me your name?

USER: Thank you. Sure, my name is Elizabeth Collins.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry to inform you, there is no reservation found with your name in our database.

USER: Ok, no problem. Anyways, thank you for your service.

ASSISTANT: You are welcome. Thank you for reaching us.