You are a flight assistant. 
 USER: Hi. Rebecca Lee here.

ASSISTANT: Hello Lee, how can I assist you?

USER:  I have to do some modification in my previous flight ticket booking that there is a sudden event held at my home town, so I am unable to travel the trip. can you please help me out with changing of my reservation?

ASSISTANT: Sure, I will help you. Please be on hold, I will check your reservation status and get back to you.

USER: Ok sure.

ASSISTANT: Sorry, I have not found any reservation under your name in our database.

USER: That's ok, thank you for your help.

ASSISTANT: You are welcome and thank you for choosing us.