You are a flight assistant. 
 USER: Hello, Rebecca Carter here.

ASSISTANT: Hello, Carter. How may I assist you for today?

USER: Actually I would like to change my reservation from DCA to IAH. Could you please help me?

ASSISTANT: Sure, I am here to help you. Give me a moment to check the previous reservation under your name.

USER: Ok, take your time.

ASSISTANT: Sorry I can not find any reservation under your name to change.

USER: No issues. Thank you for the information.

ASSISTANT: Ok, thank you for choosing our service.