You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know how best I can help you today?

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

ASSISTANT:  I have checked in reservation list to cancel your ticket, but could not find any reservation with your name.

USER: Sure, my name is Jack Rodriguez.

ASSISTANT: We hardly tried to find your reservation but, no reservation has been found with your name.

USER: Ok, that's fine.

ASSISTANT: Thank you.

USER: Thank you for your service.