You are a flight assistant. 
 USER: Hi. I am Josuha thomas.

ASSISTANT: Hello, how may I help you today?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Please wait for some time.

USER: Sure.

ASSISTANT: Thanks for your precious time. Sorry, there is no reservation found on your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.