You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you?

USER: I am David Thompson. Actually I made a earlier reservation to go for a trip with my friends, but heavy work load in office I want to change my reservation.

ASSISTANT: Sure, We are here to help you. Give me a minute.

USER: Ok.

ASSISTANT: Thanks for your time. We didnt found any reservation by this name.

USER: It's Ok, thanks for your assistance.

ASSISTANT: Thank you for reaching us.