You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

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

ASSISTANT: Sure, I will try my best to help you in changing your flight ticket reservation.

USER: Thank you.

ASSISTANT: Please wait I will check and let you know about your reservation status in my database. Ok, mean while may I know your name for easy search in my database.

USER: Sure, I will wait for your response. Sure, my name is Rebecca Thomas.

ASSISTANT: Sorry to say this Thomas, I am not able to find any reservation under your name  which you have mentioned in our booking list to change.

USER: Ok, that's fine.

ASSISTANT: Thank you for availing our agency.

USER: Thank you for your service.