You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you?

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

ASSISTANT: Sure, I am here to help you out. Please provide me your name.

USER: Sure, my name is William Gonzalez.

ASSISTANT: Sorry, there is no reservation found on your name in our reservation portal.

USER: Ok, that's fine. Anyways, thank you for your service.

ASSISTANT: Thank you for reaching us.